This is the classic in the world of pearls. The Akoya pearl was the first type of pearl that could be successfully cultured. Cultivation began in the early 20th century. Nowadays the majority of these pearls come from Japan. China and Vietnam are secondary sources. The Akoya pearl oyster (Pinctada martensii) is used to cultivate the Akoya pearl. Cultured Akoya pearls are generally between 2 and 9 mm in diameter. They are particularly appealing thanks to their intensive luster and their wide spectrum of pale hues, which range from white and rosé to crème and silver-gray.
Amethyst belongs to the quartz group and has a rich purple to pale reddish-violet hue. Heat treatment changes its color (see citrine). The most important sources of amethysts are in southern Brazil, Uruguay, and Madagascar. When the Greek god Dionysus became all too insistent in his pursuit of a nymph named Amethyst, the girl was transformed into a sparkling gemstone by the goddess of chastity. That's the story Aristotle tells to explain the origin of amethyst and its alleged ability to protect its wearer against drunkenness. That protective attribute is also the origin of the stone's name: the Greek word "améthystos" means "not drunk."
The anchor chain and the Panzerkette armor chain are two of the most classical chain forms. Characteristic of the anchor chain are the oval links, which are alternately arranged in horizontal and vertical orientation. The anchor chain is one of the strongest types of chains. It serves as the basic form for many variations: for example, the outer surfaces of the individual links can be flattened (flat anchor chain) or slightly rounded (round anchor chain).
According to legend, aquamarines come from the treasure chests of mermaids. The stone's name is derived from Latin and means "water of the sea." It earns this name with its lively, shiny hue, which ranges from pale blue to deep blue and bluish-green. The most avidly sought shade is deep blue. An aquamarine of this color is also known as a "Santa Maria." The aquamarine belongs to the beryl group. Brazil and Madagascar are the most important sources.
The baguette cut is a special type of gemstone cut. Its form is a narrow rectangular with a distinct, elongated table around which two rows of elongated facets are arranged in steps. This shape was developed in 1925 and initially used only for diamonds, then also used on other stones in ensuing years. The baguette cut is particularly suitable for transparent stones.
Not every oyster produces a perfectly spherical cultivated pearl. Just the opposite: most pearls fail to develop into flawless spheres. When they grow in various directions and unusual shapes, they're called "baroque" or "off-shape" pearls. Depending upon their specific shape, some of these pearls can be very much in demand because they can be made into unique pieces of jewelry.
The word "beryl" is used to describe a group of minerals whose members can occur in a variety of colors. If a beryl is green, it's called an emerald. If it's blue, it's known as an aquamarine. The family also includes the gold beryl, which is yellow in color, the heliodor, which has a greenish-yellow hue, and the morganite, which is pink. Other color variations are known as "noble beryl." During the Middle Ages, aquamarines were finely polished and set into the viewing windows of reliquaries, where they served as lenses to magnify the contents of the container. This practice led to the use of beryl as a visual aid in the 14th century. The German word for spectacles derives from the word "beryl."
As long ago as classical antiquity, the belief that a relationship exists between particular gemstones and certain zodiacal signs prompted people to assign particular minerals to each sign of the zodiac. The most common arrangement is given below. The stone associated with each sign is believed to have a positive, strengthening affect on people who were born under its corresponding sign. Aries (March 21 - April 20) - red jasper, carneol. Taurus (April 21 - May 20) - carneol, rose quartz. Gemini (May 21 - June 21) - citrine, tiger-eye. Cancer (June 22 - July 22) - chrysoprase, aventurine. Leo (July 23 - August 23) - rock crystal, gold quartz. Virgo (August 24 - September 23) - citrine, yellow agate. Libra (September 24 - October 23) - orange citrine, smoky quartz.
The word "brilliance" is derived from the French verb "briller," which means "to shine." Brilliance describes the luminosity of a gemstone, i.e. the overall effects of the reflected light emerging from the surface of the stone. Brilliance depends upon the reflection of incident light, which, in turn, depends upon the refractive index of the stone and the texture of the stone's surface, but is independent of the stone's color. The higher the refraction, the stronger the gleam. Diamonds are cut with the goal of achieving the ideal state of complete and total upward reflection of all incident light.
Brilliant and Brilliant Cut
When a diamond is cut with the brilliant cut, it is referred to as a "brilliant." The brilliant cut was invented in 1910 as a further development of the old cut. The brilliant cut is considered to be the perfect cut for diamonds because it optimally shows off their inherent fire, luminosity, and radiance. The proportions of a brilliant are precisely defined. Viewed from the side, a brilliant looks like two octagonal pyramids placed one opposite the other. Viewed from above, the stone appears round. The upper side has at least 32 facets which are arranged at precisely defined angles around the table. The lower part has at least 24 facets. The word "brilliant" may only be used for round diamonds that have been given the brilliant cut.
The cabochon cut numbers among the so-called "smooth cuts" in which the smooth surface of the stone is not subdivided into facets. Also known as the "mugel cut," the cabochon is the oldest known cut for gems. Connoisseurs differentiate between ball-shaped cabochons, which resemble a prone hemisphere in side view, and conical cabochons, which rise steeply to a rounded point in side view.
The word "carat" is also sometimes spelled with a "K" but is always abbreviated "ct". The carat has been used since classic antiquity as the unit of weight for jewelry stones and pearls. Carat, as a unit of weight, should not be confused with "carat" as a degree of purity for gold alloys. Both words are derived either from the Greek word "keration" (the fruit of the carob tree) or from the kuara seed of the African coral tree. One metric carat weighs 0.2 grams. Jewelry aficionados are particularly interested in the weight, i.e. the number of carats, of diamonds. A legendary type of diamond is the "one carat": i.e. a diamond measuring 6.5 mm in diameter and weighing exactly 0.2 grams. A "half carat" measures 5.2 mm in diameter. A "two carat" is 8.2 mm in diameter.
The carré cut, also known as square cut, is a quadratic shape for transparent gemstones. Its quadratic table is usually surrounded by a terraced border consisting of two rows of facets.
The citrine is a member of the quartz group. Synonyms are "gold topaz," "Madeira topaz" or "Spanish" topaz, although these citrines only superficially resemble genuine topaz because they share a similar color with that gem. The name "citrine" derives from the lemon-yellow color, although the most avidly coveted citrines are clear, luminous yellow to brownish-red. The citrine is a hard, non-fissile, and comparatively hard-wearing stone. Its primary sources are Brazil, Madagascar, and the USA. Citrine is a rather rare stone in the quartz group. Citrines occur in a spectrum of colors ranging from pale or dark yellow to golden brown. Most of the citrines sold today have been colored by firing them together with amethyst or smoky quartz. This coloring method has been a common practice for more than 200 years. When citrines are heated to a temperature between 470 and 560 degrees Celsius, their color gradually changes to the desired yellow hue.
The term "clarity" (purity) is one of the four quality criteria (the "4 Cs") according to which the value of a diamond is appraised. Absolutely perfect diamonds, which are entirely free from inclusions, are rare exceptions. The purity of diamonds is judged very strictly and classified according to an internationally accepted evaluative system. The highest grade is "IF" ("internally flawless," i.e. entirely free from inclusions). The equivalent German term lupenrein means "pure under a loupe." The other grades are as follows. VVS1 to VVS2 means "very very small included" and refers to diamonds with miniscule inclusions that are invisible to the unaided eye.
The technical term "color" is one of the four quality criteria (the "4 Cs") according to which the value of a diamond is appraised. Stones are judged by comparison with color scales. The majority of these scales have 12 quality grades. The highest grade is "very fine white," which is used to describe diamonds that are absolutely colorless. Diamonds of this quality are identified by the letters "D" and "E" or by the term "river." "Fine white" diamonds are identified by the letters "F" and "G" or by the phrase "Top Wesselton." White stones are identified by the letter "H" or by the word "Wesselton." Most diamonds are delicately tinged with color, often with a slightly yellowish cast.
Corals grow in the ocean at depths of 300 meters or less. Soft polyps very slowly build ramified structures by excreting a chalky substance from their disk-like feet. Coral is thus the scaffold of the polyps, which live in tiny indentations in the branches. Jewelry-quality coral, which primarily grows in the Mediterranean Sea and the Pacific Ocean, occurs in a wide variety of red and pink hues. Particularly desirable are the deep red variety, which experts call "oxblood" or "moro" coral, and a powdery pink variety known as "angel's skin."
The quality of a diamond is appraised according to four criteria, the so-called "4 Cs." These criteria are: color, clarity (purity), cut (polish), and carat (the weight of the stone expressed in carats).This mineral is also known as the "king" or "queen" of gems. For millennia, the diamond has epitomized hardness, immortality, and beauty. Our modern word "diamond" derives from the Ancient Greek word "adamas," which means "invincible." Indeed, this precious stone is the hardest of all minerals. It ranks highest ("10") on the Mohs' scale of hardness. Diamonds are made entirely of pure carbon. Diamonds are currently mined above all in South Africa, South America, Russia, China, Australia, and most recently also in Canada, where diamonds can be found in many different colors. The raw stones are most frequently cut in the brilliant cut.
Emerald is the name given to the most precious stone in the beryl group. The English word "emerald" is derived from the Greek word "smaragdos," which means "green stone." Most emeralds are permeated by hairline fissures and inclusions. Perfect gemstones with a rich, dark green color are rarities and are more valuable than comparably sized diamonds. The most beautiful specimens come from Colombia and typically have colorless inclusions. The beautiful green color is cloudier in emeralds from nearly all other sources elsewhere in the world. This cloudiness, however, is no longer regarded as a shortcoming and is known as "jardin. Emeralds are frequently cut and polished in the so-called terrace cut or emerald cut.
Emerald cut is the term used to describe an octagonal terraced cut that's most commonly used on emeralds because this cut best complements the character of the gemstone. The emerald has only moderately high refraction and is comparatively delicate. Furthermore, most emeralds occur in elongated crystalline shapes: the elongated shape of the emerald cut conforms with the natural shape of the gem and thus minimizes the volume of stone which is lost during cutting and polishing. At first glance, the emerald cut appears rectangular. Its octagonal shape is created by beveling the corners. Beveled corners protect the stone against damage during the setting process. Enamel is pulverized glass that has been melted at a high temperature so that it fuses onto a metal substrate. The raw material for enamel is a colorless vitreous mixture which acquires its various hues from the presence of metal oxides. Enamel powder can be sprinkled dry through a sieve or painted wet onto a substrate applied as a viscous paste consisting of powder, water, and plant-based glue. There are four different kinds of enamel: opaque enamel; transparent enamel; translucent, shimmering "opal" enamel; and painter's enamel, in which fine opaque colored powder is painted onto and then kiln-fused onto an enamel background.
Facet - faceting
A facet is a planar lateral surface that has been cut or polished on a three-dimensional stone or metal body. Facets enhance the visual effect of a faceted gem. Faceted cuts consist of a large number of small planar surfaces. This method of processing precious stones has been commonly practiced since the 15th century.
Diamonds occur in every color of the rainbow. The most common hues are yellowish, and such stones are appraised together with colorless (so-called "white") diamonds. Other colors such as green, blue, rosé and red are rarer and are collectively described as "fancy colors." The most frequent fancy colors are brownish hues and black. Rarer and more precious fancy colors include various nuances of rosé, red, green, and blue.
There are no limits to lapidaries' imaginations when it comes to the diversity of cuts that can be given to precious stones. Stars, teardrops, triangles, buds - an endless variety of shapes have been devised, many of which are new interpretations of well-known forms. Collectively known as "fantasy" or "designer" cuts, they are used in the design of diamonds and colored stones. Many of these cuts have their own specific names, although many of these names are known only by a few specialists.
As its name implies, this gem is truly born in flame. Fire opals are primarily found in hollow cavities and fissures in mountains of volcanic origin. The name is also due to the stone's intensive orange color, which gleams in nuances ranging from yellow to red. Though it belongs to the opal group, fire opal is not opalescent (i.e. it has no rainbow-colored shimmer). Most fire opals are milky and cloudy. Only the most precious specimens are clear and transparent. Fire opals can be cut into a facetted shape, which is an unusual form for cut opals. The stone, however, is inherently delicate. The most important deposits are found in Mexico.
The frame setting is like a picture frame that surrounds and firmly holds a stone. The metal is wrapped in a thin strip all the way around the stone. The closely fitting upper edge is pressed slightly over the edge of the stone, thus securely holding the gem in its desired position.
Freshwater cultured pearls are very popular nowadays. Formerly small and irregular in shape, recent advances in cultivation have made it possible to attain freshwater cultured pearls which are up to 10 mm in diameter and nearly spherical in shape. This variety of pearl is particularly attractive because of the diversity of colors in which it occurs. The spectrum ranges from white, rosé and green to intensive shades of red and lilac. To cultivate these pearls, no lifeless kernel is inserted into the bivalve: nothing is inserted except a small piece of living tissue which produces mother-of-pearl. As a result, freshwater pearls have no central kernel and consist entirely of mother-of-pearl. Freshwater cultured pearls are currently imported almost exclusively from China, whence their alternate name: "China pearls."
Garnet is a collective appellation that's used to describe more than ten jewelry stones which share a similar crystalline structure. The word "garnet" is typically associated with a red stone, but this is only true for the two most common members of the garnet group: the "carbuncle stones" pyrope and almandine. Like their relatives (e.g. green tsavorite and brown to yellow hessonite), these gems have good hardness and high refraction. Garnets are found on every continent.
Gold is one of the first metals used by mankind. Human beings have been fascinated by gold since time immemorial. The metal has a gleaming yellow color, is immune to rust, and is extraordinarily ductile and malleable. The name "gold" derives from the Old High German word "ghel," which means "shimmering" or "gleaming." The chemical symbol for gold, "Au," is derived from the Latin word for this metal, "aurum." Pure gold is very soft: before it can be used in jewelry, gold must be blended with other, harder metals to create a harder alloy. The admixture of other metals also influences the color of the alloy: the addition, for example, of silver gives gold a greenish cast.
The grading or evaluation of diamonds is known as "graduation." The appraisal is conducted in accordance with internationally recognized, objective criteria. Based on these criteria, diamonds are graded according to their color, clarity (purity), cut, and carats (weight). These four criteria are summarized under the abbreviation "the 4 Cs."
The heart cut imbues diamonds and colored stones with a touch of romance. As the name implies, a heart-cut stone is shaped like a heart. To accomplish this, a triangular or heart-shaped table is surrounded by numerous facets which enhance the gem's sparkle and gleam.
Inclusions in precious stones are like Mother Nature's fingerprints. Scarcely any precious stones are entirely free from inclusions. Most gems contain embedded foreign bodies or exhibit disruptions in their crystal structure. The inclusions can be material of the same sort (e.g. a diamond inclusion within a diamond) or of another sort (e.g. zircon in sapphire). The term "inclusion" is also used to describe cracks, hairline fissures, or hollow spaces which may be filled with liquid or gas. Inclusions can detract from the color and appearance of a stone, but many inclusions are not visible to the eye. More recently, inclusions have been recognized as a decorative element because they can cause exquisite plays of light (e.g. cat's eyes and stars). Some inclusions are so typical of a particular mineral that they can be used as proof of the stone's authenticity.
Internally Flawless is a grade of quality for diamonds and describes a stone's degree of clarity. This criterion is very strictly evaluated and classified according to an internationally recognized evaluative system. "Internally flawless" is the highest grade in this system and is abbreviated "IF." Stones of this grade have no inclusions whatsoever. A diamond is only considered to be "internally flawless" if an expert's eye can detect no inclusions whatsoever under tenfold magnification. Such perfect diamonds are rare exceptions.
Jardin is a technical term that relates to emerald. This noble gem from the beryl group is usually cloudy due to inclusions or hairline fractures. These imperfections are acceptable as long as they don't detract from the stone's lovely green color. In such cases, the lively play of colors caused by the inclusions is described as "jardin" - the French word for "garden" - and is regarded as proof of the genuineness of the stone. In no other variety of gemstone are flawed specimens so frequent and perfect specimens so rare.
When spelled with a "c," the word "carat" refers to the units used to measure the weight of jewelry stones. When spelled with a "k," the word "karat" is a qualitative designation used to describe the fineness of a metal. Every jewelry metal is an alloy which contains different metals in various amounts. Pure gold, for example, is much too soft to be used for jewelry. For this reason, gold (and certain other precious metals) are typically blended with other metals. The number of carats indicates how much of the precious metal is in the alloy. For example, the phrase "14 karat gold" means that 14 units of pure gold are contained within every 24 units of the alloy;
Random chance plays a role in the cultivation of pearls. Sometimes the oyster ejects the kernel that's been inserted into it to stimulate pearl production, while simultaneously keeping within its shell the piece of tissue that produces mother-of-pearl. When this occurs, an irregularly shaped pearl (known as a "keshi pearl") is formed. The smallest such pearls are no larger than a pinhead, whence the name "keshi," which is the Japanese word for "poppy-seed." Some keshi pearls, however, can grow as large as 10 mm in diameter. Keshi pearls occur in all species of bivalves that are used for pearl cultivation.
Kunzite, a variety of spodumene, occurs in pale pink and in shades of violet ranging from pale to dark purple with a pinkish veil. Kunzite has a lively, vitreous gleam. This attractive mineral is relatively delicate. Kunzite is extremely fissile. Brazil leads the world as the chief supplier of kunzite.
The opaque gemstone known as "lapis lazuli" is a mixture of various minerals. The chief component is lasurite, which gives this stone its typical, gleaming blue color. Lapis lazuli usually has stripes or spots of other minerals running through it. The coloration of best-quality lapis lazuli is regularly distributed; often, however, lapis lazuli is spotty or striped. The stone was used as a jewelry stone in prehistoric times. Lapis lazuli was ground to a powder and used as a natural, ultramarine blue pigment during the Middle Ages. Lapis lazuli is moderately hard. The stone is sensitive to warmth, perfume, and cosmetics. Afghanistan is its most important source.
Luster is the most important criterion in the appraisal of a pearl's value. This technical term describes the reflection of light which refracts on the many strata of aragonite in the mother-of-pearl, thereby creating a gleam that seems to radiate from the interior of the pearl. The reflected light and the gleam should seem as energetic and as deep as possible, two qualities which are associated with a thick layer of mother-of-pearl. A pearl's value is directly proportional to the intensity of its luster.
Marquise is a shape into which gemstones can be cut. The marquise cut is named after the mistress of France's King Louis XV. She loved this pointed oval shape and was particularly fond of faceted stones cut into a doubly pointed shape. A gemstone cut in this shape is similar to a navette and is likewise grouped under the main heading navette ("little ship"). A marquise diamond has a table and 56 additional facets.
Mohs Scale of Hardness
The Mohs' scale of hardness is named after it creator, the mineralogist Friedrich Mohs (1773-1839). The Mohs' scale arranges minerals according to their degree of resistance to mechanical scratching of their surfaces. The scale ranges from one to ten. Each mineral of a given degree of hardness is soft enough to be scratched by a mineral on the next highest level and simultaneously hard enough to scratch a mineral on the preceding lower level. Minerals of hardness 1 are the softest; those of hardness 10 are hardest. Gemstones having a resistance to scratching (Mohs' hardness) of 1 or 2 are classified as soft; gems in grades 3 to 5 are medium hard; those harder than grade 6 are described as hard. Values for all known minerals and gemstones have been determined on the Mohs' scale of hardness. The scale is used worldwide to classify the hardness of stones.
Morganite is the pale pink to salmon or violet-colored member of the extensive beryl family. Because of its color, this mineral is sometimes also known as "pink beryl." The name derives from the American collector John Pierpont Morgan. Among other countries, the stone's principal sources include Afghanistan, Brazil, and China.
Mother-of-pearl is produced by soft-bodied animals, the so-called "mollusks." The mollusks include marine mussels and snails that have so-called "epithelial cells." These cells, which produce mother-of-pearl, are responsible for building and growing the mussel's shell. Mother-of-pearl primarily consists of calcium carbonate, a molecule which contains calcium, carbon, and oxygen. Calcium carbonate occurs in pearls in the form of aragonite, which covers the interior surface of the shell in countless thin, parallel layers or collects around a core like the skins of an onion to produce a pearl. Like a mosaic, each of the paper-thin layers of aragonite consists of countless plate-like aragonite crystals. The cement that connects these crystals to one another is a horn-like, organic substance known as "conchyne." Mussel shells made of mother-of-pearl have been used in utilitarian decoration and ornamental jewelry for thousands of years.
The navette cut is a narrow, pointed oval shape that resembles a little ship, hence the name. This form's table is elongated, tapers to twin points, and is surrounded by facets. The shape of the navette cut is similar to that of the marquise cut.
The old cut was invented during the 19th century and is the direct predecessor of the brilliant cut, which has since become the cut that is most frequently used for diamonds today. The old cut is designed with a different number and arrangement of facets than later became common on brilliants. For this reason, diamonds designed in the old cut don't seem quite as fiery and luminous as brilliants. Various other historical diamond cuts are sometimes found in older jewelry; nowadays, all of them are grouped under the general heading of "diamond old cut stones."
Onyx is the name given to deep black chalcedony, which is a variety of quartz. Onyx is most frequently found as a multi-stratified stone: the material consists of many layers of black substrate and white overlaying layers. Chalcedonies in their natural state can be matte or have a waxy gleam. Stones with varicolored strata can be boiled in sulfuric acid. This treatment gives them a uniformly black appearance.
Orient pearl is the technical term for genuine pearls and/or natural pearls that form inside oysters without human intervention. Cells which produce mother-of-pearl are ordinarily found on the inner surface of the shell, for the growth of which they are responsible. Orient pearls can form when some of these cells stray into the interior of the bivalve. This can occur, for example, when a parasite drills through the shell into the body of the animal, or when a foreign body penetrates between the halves of the shell and injures the animal inside the shell. The mere penetration of a pebble or grain of sand into the interior of the shell is not sufficient to cause the formation of an Orient pearl.
As its name explicitly states, the oval cut is a smooth, oval shape for gems. This cut is derived from the brilliant cut. The chief element of the oval cut is the oval table with its surrounding facets.
Manganese and copper give it its colour. And also its magic. The first neon-blue Paraiba tourmaline was discovered in Brazil in the 1980s. Named after the site of its discovery, it is the rarest and most precious variety of tourmaline. A few additional deposits were afterwards found in Africa. But to the great disappointment of impassioned collectors, this gem remains extraordinarily rare. Stones weighing more than one carat are seldom found.
Pavé, the French word for "paving," is the technical term that jewelers use to describe flat surfaces of precious metal which have been "paved" with precious stones. Small gems are set closely beside one another to create a flat plane with the least possible amount of metal visible. As a rule, the "paving stones" are of equal size and have been cut and polished in identical shapes. Each stone's upper facet, its so-called "table," should lie in precisely the same plane as all the other tables in order to achieve the incandescent, luxurious appearance of fine pavé.
Peridot is a truly heavenly gemstone. It has been found in meteorites that fell from outer space and landed on Earth. Terrestrial deposits occur at sites in northern Burma, Australia, Brazil, and elsewhere. The favorite gem of the Baroque era, peridot is particularly appealing thanks to its light pistachio or olive-like yellowish-green color. Peridot numbers among the few precious stones that occurs in only one color. The characteristic olive hue prompted mineralogists to also refer to this mineral by the name "olivine."
Piqué is a technical term used to classify the purity (clarity) of diamonds. Clarity is one of the four quality criteria (the "4 Cs") according to which the value of a diamond is appraised. Absolutely perfect diamonds, i.e. stones which are entirely free from inclusions, are very rare exceptions. According to an internationally recognized evaluative system, diamonds which clearly reveal inclusions to an unaided eye are assigned to the "Piqué" group, which, in turn, is further subdivided into three subclasses: Piqué I, Piqué II, and Piqué III.
Platinum was not used in jewelry until the end of the 19th century. This metal received its name from Spanish conquistadors in South America, who called it "platina," which means "little silver" in Spanish. Platinum is the rarest and most precious of all metals. Difficult to mine and laborious to isolate from its ore, platinum is brittle and tough to work with. The alloy that's most commonly used for jewelry is 950 platinum, which means that there are 950 grams of pure platinum in every 1,000 grams of jewelry metal. The "PT 950" hallmark identifies this quality of platinum.
Polishing refers to the fine treatment given to the surfaces of pieces of jewelry. The goal is to create a smooth and very glossy surface. Polishing can be performed by hand, for example, with a piece of polishing wool, or by machine, usually with a rotating disk made of either leather or wool. Polishing can also be accomplished with the aid of polishing pastes. These preparations enhance the smoothing effect of the polishing. The several phases in the work can be performed either electrochemically, chemically, or in special polishing drums. Pieces of jewelry that show traces of wear can be re-polished by a goldsmith so that they regain their original gleam.
Princess Cut (photo)
The princess cut is a combination of the brilliant and the emerald cuts. There are several different version of the princess cut. The number of facets can vary depending upon the particular version, and the quadratic shape can be cut into a sharp-cornered or blunted carré.
The prong setting is a very characteristic setting with slender metal claws that clasp a gemstone like the fingers of a hand. The lightweight and open setting allows the color, fire, and beauty of gem to fully express themselves. Because the gem is held in place by slender pins, the stone itself appears comparatively large and can receive plenty of light. The prong setting evolved from the claw setting in which a gem was held within claws that had been sculpted to resemble the talons of a predatory bird.
The term "purity" ("clarity") is one of the four quality criteria (the "4 Cs") according to which the value of a diamond is determined. Absolutely perfect diamonds, i.e. stones which are entirely free from inclusions, are rare exceptions. The purity of diamonds is rigorously appraised and classified according to an internationally recognized evaluative system. The highest grade is "IF" ("internally flawless," i.e. no inclusions whatsoever). German-speaking jewelers sometimes use the synonymous word "lupenrein," which means "pure under the loupe," to refer to "IF" stones. Additional grades are: "very very small inclusions" (VVS1 to VVS2), i.e. with miniscule inclusions that are invisible to the naked eye, and "very small inclusions" (VS1 to VS2),
The word "quartz" describes a large group of minerals that includes many well-known varieties of jewelry stones with identical chemical compositions and similar physical properties. Mineralogists differentiate between quartzes whose crystals are visible with the naked eye (e.g. amethyst, citrine, and rock crystal) and quartzes whose crystals are microscopically small (e.g. agate, chalcedony, and jasper). Quartz occurs in every conceivable color and is used in a variety of technologies. It serves as a raw material for the glass and ceramics industries, and quartz crystals are used as components in optical, electronic, and communications applications.
The "radiant" is a special cut for diamonds. This cut is derived from the brilliant cut, but it has more facets than the brilliant cut ordinarily has. Developed by an American named Henry Grossbard, the radiant cut has exactly 70 facets, which give it its characteristic appearance.
Rhodium plating is a process by which the surface of a piece of jewelry is coated with a thin layer of rhodium. Closely related to platinum, rhodium is a very hard metal with a clear, white gleam. Rhodium is used to give a fresher look to the often grayish shimmer of white gold alloys. The layer of rhodium also frequently serves as a protective coating: for example, for items made of silver, because rhodium does not oxidize. Rhodium plating is applied to jewelry after it has been submerged in a galvanic bath.
Rhodolite is actually a pyrope, but has been given a name of its own because of its distinctive rose-red color. Pyrope belongs to the garnet group and was a fashionable stone in the 18th and 19th centuries. The name "rhodolite" is sometimes also used to describe rose-red almandines.
Rubellite is a variety of tourmaline. It occurs in colors ranging from pink to red, sometimes with a purplish tinge. Depending upon its hue, a rubellite may also be described as a "red tourmaline" or a "pink tourmaline."
Ruby received its name because of its color: the Latin word "rubens" means "red." One of the world's most valuable precious stones, a ruby can often be much more precious than a diamond of equal size because immaculate rubies are extremely rare. The most avidly sought stones come from the mines of Mogok (Burma) and have a unique color called "dove's blood" - a special shade of red covered with a breath of blue. Thailand, Sri Lanka, and Tanzania are important sources of rubies. It wasn't until 1800 that the ruby was recognized as a member of the corundum group. Prior to that date, the word "ruby" was also applied to red spinel and garnet, or else all three were simply called "carbuncle stone." In the past, the ruby was regarded as a symbol of power, courage, and dignity. During the Middle Ages, it was widely believed that a ruby would darken whenever ill luck or misfortune was imminent.
This name can lead the unwary astray: the word "sapphire" is derived from the Greek word for "blue." But sapphires, which belong to the corundum group, occur in every color of the rainbow. Sapphires can be green, yellow, pink, or brown, and each bears the name of its color as a cognomen. When a stone is described simply as a sapphire and without any additional modification, then one is typically referring to the blue variety of sapphire. The red member of the corundum family goes by the name "ruby" and the orange-colored member is called "padparaja." Sapphires rank among the most avidly sought gems. Stones with a deep, cornflower blue color are especially valuable. The most important sapphire deposits occur in Australia, Burma, Sri Lanka, and Thailand.
Precious stones typically embody the focal points of a piece of jewelry. During the long history of the goldsmith's art, jewelers have devised a variety of settings which hold the gem securely while simultaneously enabling it to optimally reveal its inherent color, light, and fire. Although the crafting of a setting is a task for a goldsmith, the actual insertion of a gem into its setting is performed by a specially trained craftsman known as a "setter." (See also prong setting and frame setting.)
Silver is a white, shiny, readily malleable and ductile metal. It has a number of superlative characteristics: for example, it is the most highly reflective of all metals and the best conductor of heat and electricity. Thanks to these attributes, silver isn't solely coveted for use in jewelry, but is also frequently used in chemical apparatuses, as well as in medical and electro-technical applications. The chemical symbol for silver is "Ag." This abbreviation is derived from silver's Latin name, "argentum." Pure silver is too soft for most applications, so it is usually alloyed with other metals. The phrase "sterling silver" describes an alloy in which 925 parts of pure silver are contained within every 1,000 parts of the alloy.
The word "solitaire" is derived from the French language, in which it means "solitary," "alone," or "eremite." When used in the jewelry context, the term refers to a piece of jewelry which features a single, usually large diamond as its focal point. The term is often used exclusively to describe a ring in which a solitary, stately diamond is the undisputed focus of attention.
South Seas Pearl
South Seas pearls are the finest and most precious of all pearls. Their size alone, which ranges between 10 and 20 mm in diameter, makes them particularly opulent. Pale South Seas pearls have a thick layer of nacre which may vary in color from white to silver, cream, gold, or even a pale bluish-gray. It is this nacre which gives them their gleaming luster. The largest and most beautiful South Seas pearls come from Australia. Indonesia is also an important producer. South Seas pearls grow inside bivalves of the species Pinctada maxima. The rarest and most costly South Seas pearls are white and almost perfectly spherical.
No two pearls are exactly identical. Even if they come from the same species of bivalve, there can still be tremendous differences in quality. In addition to the size, shape, color, and luster, another important criterion used to determine the value of a pearl is the nature of its surface. Uniform regularity is the most important criterion for the surface: the fewer ridges or indentations, the better the quality of the pearl. Pearls with perfectly immaculate surfaces are uncommonly rare because, after all, a pearl is a natural product.
Lapidaries use the word "table" to refer to the upper polished surface of a jewelry stone. This planar surface, which creates the impression of depth in the stone, is typically surrounded by numerous facets. In baguette-cut or emerald-cut gems, these facets are arranged like tiny steps. The brillia
The Tahitian pearl is the dark variant of the South Seas pearl. Above all in French Polynesia, Tahitian pearls have been cultivated since the 1960s inside the black-lipped pearl-bearing bivalve Pinctada margaritifera. These pearls reach impressive sizes between 8 and 12 mm, and may occasionally even exceed 15 mm in diameter. Their rich luster gleams in shades of gray, silver, and black, and is sometimes covered with a breath of shimmering red, blue, or green. The most avidly sought hue is called "peacock," which has a dark greenish shimmer similar to the showy feathers of the bird for which it is named.
Tanzanite is a relatively young beauty, but it isn't a new mineral. First discovered in 1967, tanzanite is a specially colored variety of zoisite and has thus far been found only in Tanzania. The stone's appeal derives from its usually immaculate transparency and intensive blue color, which can sometimes verge towards violet. Some tanzanites are bicolor and covered with a purplish tinge.
The teardrop cut is a particularly charming type of cut. As its name states, teardrop-cut gems have been cut and polished into the shape of a droplet. The table too is shaped like a teardrop, and this shape is further emphasized by the design of the surrounding facets. The names "briolett," "poire" (French for "pear") and "pampel" are also used to describe stones which have been cut into teardrop shape.
The terrace cut is one of the facetted cuts. It has a rectangular shape. The rationale for the name becomes apparent when one views this cut from the side: the terraced shape has characteristic "steps" leading upwards to a flat top or "table." This cut has been further evolved to create the emerald cut, in which the four corners of the rectangle are blunted.
The value of a diamond is determined according to internationally recognized criteria (the so-called "4 Cs"). The most important criterion is the color, which is defined according to an internationally uniform color scale. This scale is usually subdivided into 12 gradations. The top of the scale is the highly fine white known as "river." The lowest end of the scale is reserved for the toned colors, which have a more or less intensive yellowish tone and which are known, for example, as "Cape." This yellowish tone is first readily visible in stones graded "Top Cape" and is further subdivided into various grades that are assigned letters from "M" to "Z."
No longer in widespread use, the phrase "Top Wesselton" describes a particular color of diamond. Second only to river, Top Wesselton is the second-highest grade of a diamond's color and describes a "fine white." In the CIBJO's international color scale, this level of quality is subdivided into "fine white +" and "fine white" and given the letters "F" and "G."
The name "topaz" was not uniformly applied in the past, when it was used to refer to all yellow, golden brown, and sometimes also green gems. Nowadays topaz is sometimes also called "precious topaz" and designates a group of gemstones whose members occur in many different colors. Most of the colors are pale or pastel, and their hues range from yellow to blue and from green to red and violet. The most valuable topazes have colors ranging from pink to reddish orange. Topaz most commonly occurs as a yellow stone, which sometimes causes it to be mistaken for citrine. Topaz, however, is harder and more refractive than citrine. The only weakness in topaz is its easy cleavage. Brazil is the most important source of topaz.
The tourmaline group includes stones which occur in a wide variety of colors. Some color variants have names of their own, e.g. tourmalines whose colors range from pink to red are known as "rubellite." Black tourmalines are also known as "schörl." Green ones are termed "verdelite." Blue tourmalines are called "indigolite." Monochrome tourmalines are quite rare. It is much more common for a tourmaline to exhibit different shades or sometimes even entirely different colors, hence the name: turmali is the Singhalese word for "stone with a mixture of colors." Brazil is the world's most important source of tourmaline.
Transparency refers to the degree to which a gem allows light to pass through it. A gem can be transparent, translucent, or opaque. Transparency is an important factor in determining the value of a gem. Inclusions or cracks detract from a stone's transparency, which is subdivided into several degrees. Specialists describe a gem as "transparent" when incident light is reflected unhindered, as "moderately transparent" when light is reflected with less intensity, and as "opaque" when light is completely absorbed.
The original, natural colors of many precious stones can be altered artificially. Irregular or unattractive nuances of color can be improved by heating the gems to a temperature of several hundred degrees Celsius. The best-known treatment is the thermal processing of amethyst: depending on the duration and temperature of the heat treatment, an amethyst's color can be changed to yellow (citrine) or green (prasiolite). So-called "firing" can give a sea-blue color to aquamarines which have a naturally greenish tinge and can brighten the hue of originally dark tourmalines. These alterations in color do not look at all artificial and do not harm the gems.
The trilliant is a cut that gives a diamond the shape of a symmetrical triangle. Diamonds cut in this shape are often set alongside colored stones or large diamonds. The "troidia" cut is another triangular cut with three convex sides and, depending on the size of the gem, from 77 to 107 facets.
No other mineral has been revered as a holy stone and talisman by so many cultures around the world. Mankind has perennially been fascinated by turquoise and its opaque, sky-blue to apple-green color. The name, which means "Turkish stone," recalls the days when turquoise reached Europe along trade routes that passed through Turkey. The most avidly sought color, a clear sky blue, is also the rarest hue. Most turquoises have dark veins of other minerals running through them. The best-quality turquoise comes from Iran. This mineral isn't especially hard and is slightly porous. The latter attribute makes it sensitive to perspiration, cosmetics, and perfume.
The vibrating waves of ultrasound are particularly useful to jewelers because these sound waves can be used to cleanse delicate or difficult-to-reach surfaces. The pieces of jewelry which are to undergo cleansing are immersed in a bath containing a cleaning fluid. Sound waves with frequencies above the limit audible to human ears create vibrations which loosen and remove tarnish or soiling from the treated surfaces.
The term "Wesselton" is no longer widely used. It describes a particular color of diamond. Wesselton follows river and Top Wesselton as the third-highest grade in the scale of diamond colors. It follows "highly fine white" and "fine white" and corresponds to diamonds whose color is rated as "white." This quality level is assigned the letter "H" in the CIBJO's internationally recognized color scale.
Zircon is a mineral that's full of luminosity and fire. Although its name probably derives from the Persian language and means "golden colored," zircons in fact occur in many different hues. Its refraction is nearly as high as that of the diamond, but zircons are very brittle and thus sensitive to pressure and shock. Varieties of zircon include the yellow to reddish brown "hyacinth zircon," the straw yellow to nearly colorless "jargon zircon," and the blue "starlin," which is usually produced by heating other zircons. Zircons are found in Asia, Australia, South America, Africa, and elsewhere. The natural zircon has nothing except a similar-sounding name in common with zirconia, which is a synthetic stone.
Zirconia is the man-made, synthetic stone which best imitates a natural diamond. Its physical properties are similar to those of its noble model, and zirconia achieves very good visual effects. Synonyms are "fianite," "phianite," and "CSZ" (cubic stabilized zirconium oxide). Zirconias have been manufactured in a wide range of sizes and shapes since 1977. Some zirconias have even been made with artificial inclusions. Zirconia shouldn't be confused with zircon, which is a naturally occurring mineral.