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Gemstones Information
Stones have always fascinated mankind. It has been worn upon theperson since prehistoric times . Stones play the principal part in most of Jewellery. In former centuries they were reserved for the ruling classes only. Today everybody can afford beautiful stones for jewellery and adornment. The first known, used for making jewellery, include ruby, amethyst, rock crystal, amber, garnet, jade, jasper, coral, lapis lazuli, pearl, emerald and turquoise. There is no generally accepted definition for the term Gem, but they all have something special, something beautiful about them. Most stones are minerals (e.g.diamond), mineral aggregates (e.g. jade), rarely rocks (e.g. lapis lazuli) taken from earth, improved with artistry by cutting and polishing. Some are organic formations (e.g. amber, pearls) and other gem materials are of synthetics origin.
All these materials (Gem stones) given upon are (except synthetics) naturally made without human interference & dividing in two categories.
Precious Stones
|| TOP ||Rarity, hardness, natural origin and beauty together with chemical resistance, all constitute an acceptable definition of precious stones. Nine types of stones fall in this category: 
1)
Diamond: for more
details
2) Emerald:
The name of Emerald derives from Greek word “smaragdos”. Emeralds are probably the rarest of all precious stones and are considered even more valuable then the Diamond. Emerald is basically the green variety of Beryl. The emerald is found in the rock in which it was for med and unlike diamonds, it is never occurs in gem gravels. The typical colour is a beautiful distinctive hue known, in fact, as Emerald green and is due to traces of chromium in the crystal structure. But emeralds can be light or dark green, bright green or leaf green. The shades most highly valued are those of an intense fresh green. The best emeralds are found from the mines of Columbia, South America and some also found in the U.S. mines. The biggest and most beautiful emeralds come from the famous Chivor and Mezzo mines of Columbia. Other emerald mines are in Brazil, Transvaal, Zimbabwe, Tanzania, India, Pakistan & Austria too. The most famous quality 2 colour emeralds are found from Sandawana in Zimbabwe. Emeralds of fine colour, weighing more than 2 carats are among the most highly valued and their price may equal or exceed that of Diamonds. Less ideally coloured varieties-too dark or too pale –are worth quite a lot less and if they are slightly turbid as well, the value is reduced even further.
3) Ruby: || TOP ||
Ruby is the oldest or first known of all precious stones dating back in early history. It is th us name because of its red colour. In Sanskrit it’s called “Padmarag” or “Vasu-Ratna”. It is a most valuable variety of transparent Corundum & an oxide of Aluminum. The colour ranges from pink to deep red. The most desirable colour is the so called “pigeon blood red”, pure red tinted with purple. Flawless specimens showing the most desirable colours are rare; the varieties of shades are due to the presence of a small quantity of oxide of chromium, and in the case of brownish tones, iron is present as well. As a rough stone, ruby appears dull and greasy, but, when cut, the luster can approach that of diamond. Heat treatment is commonly used to improve the colour. In whish ruby a star of rays is seen in a particular cut, is called “Star Ruby”. Ruby is the hardest mineral after diamond. The rubies with the finest colour come from the Mogok district of upper Burma (now calling Myanmar). Light red comes from Sri Lanka (Ceylon) & dark brownish-red from Thailand (Siam). Other sources for rubies are India, Pakistan and Tanzania. The highest quality, best colour and most transparent stones (usually from Burma), can be as valuable as diamonds, or even more so and exceeded in value only by emerald. Among the famous true rubies are “Anne of Brittany’s Ruby, De Long Star Ruby, Edwards Ruby, Peace Ruby and Rosser Reeves Star Ruby.
4) Sapphire: || TOP ||
The variety of transparent corundum of any colour other then red (which is Ruby) & golden (Pukhraj). The name Sapphire is probably derived from Sanskrit word “Neelmani”. Sapphire can be a very dark blue, to the point of seeming dense and blackish from a distance, sometimes accompanied by a blue to dull green pleochroism, which is only visible from the side in the cut stones.  They may also be a strong, but not to bright blue, easily recognizable from a distance this being the ideal colour. The usual and preferable best colour is pure cornflower-blue, like neck of peacock; it’s calling “MAYUR NEELAM” or “KASHMIR SAPPHIRE” because of find in Kashmir, India. Other colours available in sapphire are white, green, pink, brown, black, iron, orange, light red, & violet. Any sapphire that is not blue is sometimes called a “fancy sapphire”. Some sapphires change colour in daylight from that in artificial light. Sometimes the yellow variety of corundum called “Golden Sapphire” or “Pukhraj”, the dark green “Oriental Emerald” & the purple is “Oriental Amethyst”. Other sources of sapphire are Burma, Sri Lanka, Thailand, Cambodia, Australia, United States, Tanzania & Malawi . Among the most famous or larger sapphires are the Bismarck Sapphire, Lincoln Sapphire, Logan Sapphire, Raspoli Sapphire, St. Edward’s Sapphire, Stuart Sapphire & Gem of the Jungle, and among those that show asterism are the Star of Asia & Star of India.
5) Pukhraj (Golden Sapphire): || TOP ||
Pukhraj word derived from Sanskrit word “Pushparag”. The transparent golden variety of corundum. It’s also called “Oriental Topaz”. Many gemologists put it in sapphire category, but as astrology this is a different stone. Pukhraj is hardest stone after Diamond & Ruby. Best pukhraj is finding from Brazil, Rhodesia and Sri Lanka (called “Jal Neelam or “Ceylony”). Other sources are Japan, Mexico, Russia, Siberia, Burma, Tasmania and England.
6) Pearl: || TOP ||
Pearls have been considered from the earliest times among the most splendid gems. Pearl is composed of conchiolin and calcium carbonate. In Sanskrit pearls called “Mukta”. As in Indian earliest history pearls are dividing in nine categories:
1) Gaj-Mukta: This rarest pearl was found from head elephant.
2) Sarp-Mukta: This pearl was found from “Vasuki” Snakes. It’s of bluish shades.
3) Meen-Mukta: This type pearls found from fish stomach.
4) Bansh-Mukta: This pearls found from Bamboo tree.
5) Aakash-Mukta: This pearl fall from sky with rain drops.
6) Shankh-Mukta: Found from “Panchjanya”-Shell.
7) Megh-Mukta: This pearl fall from sky & its look like water drops.
8) Shukar-Mukta: These round yellowish pearls found in a kind of sea creature “Mother of Pearl”. Pearl is formed by saltwater oyster, some freshwater mussels, and more rarely by other shellfish. Pearls are globular, usually almost spherical cysts, which form inside the tissues of the mollusk. Sometimes, they are pear, egg, bean-shaped or display more pronounced irregularities consisting of roundish apophyges or even sharp crests. The colour is generally much the same as that of the inside of the oyster shell. Most pearls, therefore, are white with a touch of gray to yellowish gray-white, but they may be grayish, blackish or iridescent from gray to green – blue – violet and pink. Pearls assume every colour of rainbow. Pearls are composed of numerous, thin, concentric layers, which are deposited successively by the mollusk. To some extent, the older the pearl, the bigger it is, and the more numerous are the constituent layers. But in cultured pearls, which nowadays far outnumber the others, the inside consists of a spherical nucleus of mother-of-pearl, often taken from the shell of another mollusk, artificially shaped into a bead, but composed of flat, parallel layers, surrounded by a number of concentric layers of nacre deposited around it by the pearl producing mollusk.
Natural Pearls:
Natural pearls are those pearls that come into being without intervention by human being, in the ocean as well as in fresh-water.
Sea Pearl:
Pearl-producing Sea mollusks live along stretches of coast at a depth of about 50-60 feet, the various species range in size from about 2.5” to 12”; their life span is about 13 years.
River Pearls:
Fishing of natural pearls in fresh-water, the river pearls is today of no great importance commercially; they rarely of good quality.
Cultured Pearls:
A variety of pearl that is created by a mollusk in the same manner as a natural (wild) pearl except that the process is stimulated by the human insertion into the shell of a grain of sand, a bead, a piece of mantle tissue, or other irritant that becomes the nucleus of the pearl when encased in many layers of nacre. The method was first attempted in China in the 13th century and again later in the 18th century in Sweden, but it was accomplished. In 1896 by Kokichi Mikimoto who produce first a type of blister pearl (called a Mabe pearl). Latter in 1915, he and other perfected the cultured spherical pearl, for which purpose native Japanese pearl oyster have since been specially cultivated; the method involve inserting into an incision in the mantle of the oyster a peace of living mantle tissue from another oyster that enclosed a mother-of-pearl bead (letter the silver of tissue was first inserted and then the bead) and covering the hole with nacreous material and returning the oyster to the sea, where it secretes nacre to enlarge the nucleus. Such cultured pearls were introduced into the London market in 1921, and the peace of cultured pearls soon greatly dropped, especially when methods of identification were developed.
The people of India & Persia were among the earliest to collect them because of the fisheries of Ceylon and the Persian Gulf. Most of the few natural pearls harvested nowadays come from the Persian Gulf (called “Persian Pearl”, “Basra Pearl” or Basarai Moti”), South India (called Tutikorean pearl), Sri Lanka, the Red Sea & the Philippines; some small quantities also come from the sea of Venezuela, Australia, Japan and from the Gulf of California. The cultured pearl mostly comes from Japan, India, Australia & China.
Value of Pearls:
Pearl is a most valuable gem in antiquity. It’s valued according to shapes, colour, size, regularity-of-form, compactness, surface condition and luster. The most valuable is the spherical shape. Those flattened on one side or half-spherical pearls are called “Button Pearls” and irregular pearls are baroque pearls. The more watery, translucent ones are less durable; therefore less valuable. In the case of a number of a pearls in a peace of jewellery, much depends on their infirmity of colour or, at any rate, how well matched they are. A string of pearl of equal diameter is worth much more then one consisting of pearls of graduated diameters (larger at the center, smaller at the ends), because numerous pearls of a uniform size are harder to find. Even a pair of matching pearls is worth more than double the peace of a single pearl, because of the quantities that have to be sorted to find two that are identical. Manu natural pearls are old or antique and when they are in a poor stage of repair, dehydrated or cracked, brittle or yellowed with age, their value is greatly reduced.
Pearl & Pearl Jewellery Care
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Coral: || TOP ||
Coral is a branching skeleton, like structure built by small marine animals – Coral Polyps related to reef forming corals. This process is done at a fix temperature. So coral is not found in every sea. The coral is found at depth of approx 10 to 1000 ft, and mainly harvested with weighted, wide meshed nets dredged across the seabed. The height of branches is in the general range 20-40 cm; the branches are up to 6 cm. thick. Calcium carbonate in the form of calcite is the main constitute of coral. When harvested by divers, however, not as many corals are damaged. When it is bought of the surface, the soft parts are rubbed away and the material is sorted as to quality. The skeletons of corals vary in colour: from bright to dark red (ox-blood red), slightly orange-red, light to deep-pink, yellow, blue, black and white. (In the past, blue corals are found at the sea sore of the Africa. But they are not available now.)
Coral is found in Mediterranean Sea, the Red sea, Bay of Biscay, Canary Island, Malaysian Archipelago, the Midway Island, Japan, Hawaii, Algeria, Junisia, Corsica, Sarilinic, Sicily, Italy, Adriatic Sea and Spain. Most desired of all coral types. According to place of discovery, it has numerous trade names. The colour is uniform: light red to salmon colourd- Momo, medium red- Sardegam, ox-blood red- Moro, tender pink with whitish or light-reddish spots- Angel Skin coral. Coral is mainly used as beads as set in ornaments as Cabochon. Also used for showpieces.
Cat’s Eye: || TOP ||
It’s a variety of chrysoberyl. Fine parallel inclusions produce a silver-white line, which appears as a moving light ray in a cabochon cut stone. The name Cat’s eye is derived from this effect, which reminds one of the pupils of a cat. Cat’ eye is available in golden-yellow, green-yellow, green, gray-green, brownish & red colours. Its deposits in Sri Lanka, Brazil, India, China and Zimbabwe.
Zircon: || TOP ||
The name Zircon may be derived from the Arabic word zarkun (meaning-red) or from the Persian word zargun (meaning- golden yellow). Zircon is found in isolated crystal or as twins, in the form of squat prisms with bipyramidal terminations, sometimes  cloudy, opaque, but often transparent with considerable luster. They are usually small. They can be light brown or gray, also reddish-golden (cow urine), light brown, yellow, reddish, green, blue, greenish-blue or colourless. In nature the red-brown and gray-brown zircon are the most common. Colourless are rare. Deposits of zircon in mostly available in Sri Lanka, Burma (Myanmar), Cambodia, Thailand, Australia, Brazil, Korea, Madagascar, Mozambique, Nigeria, Tanzania and Vietnam.
Semi-Precious Stones:
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TOP ||
Agate
Almandine
Alexandrite
Amazonite
Amber
Amethyst
Apatite
Aquamarine
Aventurine
Azurite
Beryl
Blood stone
Calcite
Carnelian
Chalcedony
Chrysoberyl
Chrysoprase
Citrine
Corundum
Dolomite
Fluorite
Garnet
Iolite
Ivory
Jade
Jasper
Lapis (Lazuli)
Malachite
Moonstone
Mother-of-Pearl
Opal
Onyx
Peridot
Pyrite
Quartz
Rhodochrosite
Rose Quartz
Rhodolite
Smoky Quartz
Spinel
Tanzanite
Tiger’s-Eye
Topaz
Tourmaline
Turquoise (Froza)
Synthetic Stones
A large number of
stones used in jewellery are semi-precious. The most
importance ones are here:
Agate: II TOP II
Agate is the most familiar of the sub-verities of chalcedony. It is commonly composed of alternating layers of difference thickness, colour & porosity that tend to parallel the walls of the rock cavity in which it was deposited. The natural colours being 1) in intercalated bands distinctly marked from each other- called “banded agate”, the difference in the bands being due to degrees of transparency and colour and to inclusions of milky layers alternating with layers of quartz, jasper, cornelian or onyx. 2) In cloud-like, moss-like or dendrite form. It available in many parts of the world & was used extensively in Egypt and Rome, in ornamental pieces and in jewellery such as beads & brooches; in the Middle Ages it was worn as an amulet or talisman. Also used for wall peaces, in watches & in aquarium.
Almandine: II TOP II
It’s never occurs pure in nature but for convenience, gems near the end of the almandine- pyrope solid solution series are called almandine. It’s a variety of garnet that is transparent and commonly deep crimson with tinges of purple. Mainly the colour range is from red-violet to dark brownish-red. It, colour may resemble that ruby.
Alexandrite: II TOP II
A variety of chrysoberyl like cat’s eye. This is a very attractive but costly stone. Due to the presence of oxide of chromium, it appears dull grass-green by day-light (which is rich in blue rays), but by electric light is appears yellowish or reddish-yellow and by soft candle-light (which is rich in red rays) it appears reddish. Best alexandrite comes from Russia, Burma (Myanmar), USA, Madagascar, Brazil and Ceylon.
Amazonite: II TOP II
Amazonite is also called “Amazon Stone”, because of Amazon River; where formerly green coloured stones found. Amazonite is a light green to bluish-green coloured with white mottled flecks. It is a non-transparent or translucent stone. It’s mostly found in Brazil, United States, Zimbabwe, Australia, Russia, Namibia and Colorado.
Amber: II TOP II
Amber is a one of organic gems which produce by biological process, whether animal or vegetable. An amorphous translucent or opaque fossilized natural resin from an extinct variety of pine tree submerged under the sea some 50 to 60 million years ago. It is light in weight, warm to the touch, very brittle and electrified when rubbed. Its colour covers a wide range, usually from yellow to honey, brown or reddish-brown; it some times has a dusty, friable reddish-brown, light brown or gray crust due to alteration. It is found in variously shaped nodules. Mainly amber is find from Baltic States and the Dominical Republic. Other sources of amber are Russia, Kaliningrad, Lithuania, Estonia, Latvia, Poland, Denmark, Myanmar (Burma), Lebanon, Sicily, Mexico, Romania, Canada, England and Norway.
Amethyst: II TOP II
A transparent and crystalline variety of Quartz, usually deep purple to pale-purple or bluish violet, reddish-mauve, reddish-violet and gray-mauve coloured. Amethyst is found from Brazil,  Madagascar, Zambia, Uruguay, India, Burma (Myanmar), Canada, Mexico, Namibia, Russia, Sri Lanka and United States. The best stones are faceted; others are tumbled & beads used in jewellery. When natural amethysts (not the variety from Madagascar) are heated, the colour changes to pale yellow; when the heat is increased, it changes to dark yellow or reddish-brown and when increased further, to milky white. Some Brazilian amethysts when heated change colour to green. There are some amethysts that lose some colour in daylight. The original colour can be restoring by X-ray radiation. Amethyst is also used as a hilling-stone in Fang-Sue.
Apatite: II TOP II
The name is derived from Greek word “apate”, means to deceive. Basically apatite is known for its asparagus-green colour but also available in other wide varieties of colours like pink, blue, greenish-blue, violet, yellow and colour-less too. Deposits of apatite are in India, Burma, Brazil, Kenya, Madagascar, Mexico, Sri Lanka, Norway, South Africa and United States.
Aquamarine: II TOP II
It’s a variety of beryl that is transparent and of various shades of blue and blue-green . Aquamarine is so named because of its seawater colour. In Latin it’s called “water of sea”. The stones are diachronic, brittle and sensitive to pressure. Most aquamarine comes from pegmatites of Brazil, where crystals weighing several kilos have been found. Other deposits are in India, Soviet Union, Madagascar, United States, Afghanistan, China, Kenya, Mozambique, Namibia, Nigeria, Zambia and Zimbabwe. The largest aquamarine was found in 1910 in Marambaya, Minas Gerais (Brazil). Rich blue stones several carats in weight are among the most valuable of secondary gems. They are worth a lot more, for instance, than blue topaz of similar characteristic. Pale or green stones are less valuable. Because of its cool and attractive colour, aquamarine is favorite gem of all modern designers.
Aventurine: II TOP II
The name aventurine is applied to an ornamental material consisting mainly of quartz. The granular appearance, the possible presence of distinct green fibers, and its particular translucence are the most distinctive characteristics. It’s available in soft-green, silvery, yellow, reddish-brown, greenish-brown, orange and bluish-green. Aventurine comes mostly from India, Soviet Union, Brazil, Tanzania and Australia. Very modest, when as is usually the case, the material is whitish to grayish or dull green, and the workmanship is of a low level. But expertly fashioned, bright green stones are more valuable. Aventurine used for jewellery and other ornamental pieces from many centuries.
Azurite: II TOP II
Azurite is a blue copper carbonate, so-called because of its intense azure-blue colour. It occurs at the same localities as malachite and although less abundant, the two minerals are almost invariably associated. Azurite in places occurs in well-formed monoclinic crystals. It has a vitreous luster. Exceptional dark blue –almost black crystals have come from Namibia, Morocco, Australia, Chile, Mexico, Russia and United States.
Beryl: II TOP II
Beryl is a mineral with several gem varieties covering a wide range of colours. Deep green beryl are called Emerald (one of the most valuable of all gems), blue – aquamarine and other colours called precious beryl. The name beryl comes from India and has always been associated with the gemstone. Beryl is also the most abundant mineral containing beryllium and is the chief source of this rare light element with many important industrial uses. Main colours found in beryl are emerald-green, sea-green (Emerald), blue (Aquamarine), raspberry-red (Bixbite), all shades between lemon-yellow & golden-yellow (Golden Beryl), colourless (Goshenite), light yellow-green (Heliodor), soft pink to violet (Morganite or Pink Beryl) and pale-green, bluish-green, yellowish-green (Green Beryl). Deposits of beryl are in India, United States, Brazil, Namibia, Madagascar, Nigeria, Sri Lanka, Zimbabwe, China, Canada, Mexico, Russia and Afghanistan.
Blood stone: II TOP II
Blood-stone is an opaque, dark-green or blackish-green chalcedony with red spots. An old name still used in Europe is heliotrope. The most important deposits are in India, also found in Australia, Brazil, China and United States.
Calcite: II TOP II
Calcite is a very common mineral that occurs in a wide variety of colours, texture and forms. It is the predominant or only mineral of limestone, marble and onyx marble, all used as ornamental stones.
Carnelian: II TOP II
Is probably named after the colour of the kornel cherry because of its colour. Carnelian is variety of chalcedony that is usually flesh-red, but also ranges from yellowish-red to reddish-brown translucent or opaque. The colour is intensified by heating. The stone is sometimes mottled by flecks of the matrix. It is hard and tough, and so is often carved in intaglio from all the seal, or used as beads. Deposits are found from India, Brazil and Uruguay.
Chalcedony: II TOP II
This is the name given to the microcrystalline varieties of quartz. However because of colour variation or banding, sub varieties of chalcedony are given special names. Specifically, chalcedony is a honey-yellow to gray, translucent or opaque stones with waxy luster. But for ornamental purpose, the types that have been variously coloured by small quantities of other elements are usually used. These colours are brownish-yellow, red, black, green, black & white, Gray & white, yellow, brownish-red and almost all shades of these colours with milky look. Sometimes in several colours blended into each other. It is commonly found with agate as in Uruguay & Brazil; it also found in India, Madagascar, Namibia, Zimbabwe, Sri Lanka and California.
Chrysoberyl: II TOP II
The name chrysoberyl is derived from Greek chryso (golden). The colour varies of
chrysoberyl is from golden-yellow and brown to yellowish-green or bluish-green, also available in green and pale yellow. The dark green variety is called alexandrite. A colourless variety is rare. Chrisoberyl is mainly found from Brazil, Sri Lanka and Madagascar.
Chrysoprase: II TOP II
It is considered the most valuable stone in chalcedony group. By the presence of a nickel compound, chrysoprase is an apple-green coloured. It used as cabochons for necklaces and ornamental objects. In earlier centuries, it was used as a luxurious decorative stone for interior decoration. Chrysoprase mainly comes from India, Germany, Soviet Union, United States, Canada, Brazil, Australia, Kazakhstan, Madagascar, Zimbabwe, South Africa, Tanzania and California.
Citrine: II TOP II
Pale to dark yellow, lemon yellow and golden-yellow quartz. It is commonly mistaken for and  sometimes sold as the more valuable topaz. Natural citrines are rare. Most commercial citrines are hear-treated amethyst or smoky quartz. Brazilian amethyst turns light yellow at 470 degrees C. Some smoky quartzes turn into citrine colour already at about 200 degrees C. Almost all heat-treated citrine have a reddish tint. The natural citrines are mostly pale yellow. Deposits of natural colour citrine are found in Brazil, Madagascar, United States, Argentina, Burma, Namibia, Russia, Scotland and Spain.
Corundum: II TOP II
The hardest mineral other than diamond. The name corundum has its origin in India and probably referred to ruby. Its found in two varieties, 1) common corundum, which is impure, coarse, opaque and granular, and used as an abrasive; 2) transparent corundum, which included three of the most important precious stones, Ruby, Sapphire & Pukhraj. Corundum exhibits a wide range of colours like: blue, green, pink, yellow, golden etc.; and such stones are properly termed sapphires preceded by the appropriate colour, except that the red variety is called Ruby. Common corundum is a relatively abundant mineral, and because it is surpassed only by diamond in hardness, tones are mined each year for use as an abrasive. This superior hardness also contributes greatly to the value of this mineral as a gem. Ruby, sapphire & pukhraj have been highly priced since ancient times, and much lore and legend are associated with them. Corundum is mostly found from India, Burma, Thailand, Sri Lanka, Tanzania, Cambodia, Australia, United States & Malawi.
Dolomite: II TOP II
It’s a colourless, transparent mineral, sometimes also available in pastel colours.
Fluorite: II TOP II
It has a vitreous luster; colour distribution is often zonal or spotty. Mostly found in Germany, Argentina, England, Burma, France, Namibia, Austria, Illinois and Switzerland.
Garnet: II TOP II
This is a group of differently coloured minerals with similar crystal  structure and related chemical composition, some varieties being so close as to be difficult to differentiate. The traditional colour is dark red, but the stones are found in many colours & shades, depending on the chemical composition. The main representatives are grossularite (hessonite, rosolite), pyrope (rhodolite), almandine, andradite, spessartite & uvarovite. Garnets were mostly used in Indian traditional ornaments, Anglo-Saxon jewellery, and Victorian jewellery; also used by Egyptians, Greeks, Romans and Celts. Deposits of garnet are found in India, Brazil, Burma (Myanmar), China, Madagascar, Sri Lanka, United States, Namibia, South Africa and Tanzania.
Iolite: II TOP II
It is the Greek-blue or sapphire-blue gem variety of the mineral known as Cordierite. It is also called Dichroite. Water sapphire is misleading name early applied to the gem. It has greasy vitreous luster. Mostly found in Burma, Brazil, India, Sri Lanka, Madagascar and United States.
Ivory: II TOP II
Originally ivory is a hard, creamy-white, opaque dentine that forms the tusks of elephants. Today it is also the teeth of hippopotamus, narwhal, walrus, wild boar and fossilized mammoth. It is translucent when cut in thin sheets. It is initially white but ages with a yellow or brownish patina, and is mark with delicate horizontal graining. Different ivories show different colours under ultraviolet light. Because it is relatively soft and easily worked, ivory has been a favored medium for carving since the earliest civilization. It has long been used for jewellery in the form of finger rings, pendants, brooches, beads, bangles, buckles, pins etc... and for ornamental purpose. Because of ivory is a dentine, it confused with bone. Since 1989, there has been a worldwide ban on any trade in elephant’s ivory. Most ivories come from India, Africa, Burma and Indonesia.
Jade: II TOP II
Two distinct and unrelated species, jadeite & nephrite called Jade. Differentiation between jadeite & nephrite is based on properties, but the term jade is used as a description of both. Jade is available in green & other colours too. The gem which had been known from 7,000 years was used for arms and tools, Chinese used for making weapons and ritual ornaments because of exceptional toughness. The green variety of jade, nephrite - Chinese called “yu”, and also known as axe-stone; found from Burma, Australia, New Zealand, Brazil, Mexico, China, Central America, Canada, Zimbabwe, Russia, Taiwan Alaska and Poland.
Jasper: II TOP II
In earliest history jasper is known as “Spotted stone”. It is usually consider as chalcedony or  agate, some scientists put it in a group because of its grainy structure. Mostly used for ornamental purpose. It is nearly opaque with a dull luster and usually admixed with other material. Jasper is available in red, white, brown, yellow & other colours. Deposits of jasper are found from India, Australia, Canada, Brazil, Madagascar, Russia, Uruguay, Kazakhstan and United States.
Lapis (Lazuli): II TOP II
Lapis lazuli is a gem material consisting of a complex mixture of several minerals. In addition to the feldspathoid mineral group, plus calcite, pyrite, and often small amount of augite, hornblende and mica, therefore, lapis is not a mineral, it’s a rock. It is a translucent or opaque. It is a strong but lively blue, sometimes with a violet tint. In lapis contains grayish, off-white or golden patches. Lapis lazuli is sensitive to strong pressure and high temperatures, hot baths, acids and alkalis. Rings should be taken off during household work. It mostly found from Afghanistan, Russia, Chile, Myanmar, Canada, Colorado, California, Pakistan and Angola.
Malachite: II TOP II
It also called “Kidney Stone” because it was supposed to cure kidney ailments if applied to the side of the body.
Moonstone: II TOP II
Is a most important and translucent variety of feldspar, shows a blue-whitish, pinkish-white, peach-white or yellowish-white opalescence, which glides over the surface when moon-stone is cut as cabochon. The name moonstone because if put in a moonlight it’s look like a snow-peace. It is available in India, Myanmar, Brazil, Sri Lanka and Madagascar.
Mother-of-Pearl: II TOP II
Mother-of-pearl is an organic gem material, is an inner material of a mollusk shell. In jewellery mother of pearl of the pearl mollusk is mostly used. Basic colour of mother-of-pearl is basically white with rainbow; it is naturally dark in mother of pearl from Tahiti pearl. The mother-of-pearl of pearl mollusk is called sea opal, because of a resemblance to the colour effects seen in opal. Mother-of-pearl used as costume jewellery and also supporting character for diamond and gold jewellery.
Opal: II TOP II
The name opal is derived from Indian- Sanskrit word for stone. A gem opal is usually characterized by a flashing mixture of prismatic colours of delicate huge when light falls upon the surface. It dose not have a crystalline form, but is amorphous, gelatinous, hydrous silica containing a variable percentage of water, with traces of impurities that are oxides of various metals. Opal is available in two varieties: 1) Precious opal and 2) Common opal. There are many sub-varieties in opal - white opal, black opal, opal matrix, boulder opal, harlequin opal, jelly opal, crystal opal, fire opal, agate opal, wood opal, honey opal etc… Opal is a sensitive to pressure and knocks as well as being affected by acids. Opal is found from Australia, Brazil, Guatemala, Honduras, Indonesia, Japan, Mexico, Russia, Idaho and Nevada.
Onyx: II TOP II
Onyx is a variety of chalcedony that is very porous and is composed of parallel straight layers of different shades of black and white. Many other signal colours are available in onyx. Almost all onyx is artificially coloured. It is translucent or opaque variety.
Peridot: II TOP II
Peridot is also called “Ghrut-mani” in Sanskrit, because of it’s coluor like “Cow-Ghee”. An olivine variety of gem with golden-green, and also shades ranging from dark leek-green to yellowish-green are available in peridot. It has been confused with green corundum or chrysoberyl. Peridot is found from Sri Lanka & Egyptian island of St John’s in the Red Sea.
Pyrite: II TOP II
Pyrite is one of two metallic minerals used as gemstones; the other is hematite. It is pale brassy-yellow and has a brilliant metallic luster. It is the most common and abundant of the several minerals collectively known as “fool’s gold”.
Quartz: II TOP II
Quartz is the name for a group of minerals of the same chemical compassion and similar physical properties. It is one of the most widely distributed mineral in the earth’s crust, sometimes found as elegant crystals whose luster, hardness and watery transparency or conversely, pleasing colours have long been a source of fascination, causing it to be widely employed as a gem or ornamental material. Rock crystal (colourless quartz), amethyst (light to deep purple), smoky quartz (brown to black, smoky gray), citrine (light to dark yellow, golden-brown), prasiolite (leek-green), rose quartz (baby pink), aventurine (green, red-brown, golden-brown), prase (green), blue quartz (turbid-blue), cat’s eye, tiger’s eye, hawk’s eye are the varieties of quartz group.
Rhodochrosite: II TOP II
Rhodochrosite has been on the market only since about 1940. Because of its lovely rose-red colour, it is most desirable ornamental stone. Other main colour is raspberry-red. Its attractiveness is enhanced by its usual variegated nature in which red bands. Deposits of rhodochrosite are found from Mendoza, Mexico, Peru, Chile, United States and South Africa.
Rose Quartz: II TOP II
The name rose quartz is because of its baby pink colour. The colour of this stone often fades in sunlight. Rose quartz is usually turbid, rarely transparent and the colour is presumably due to small amounts of titanium. Rose quartz is pegmatite mineral and is found in large amount at many localities, but deep coloured flawless material is rare. Deposits of rose quartz are found from India, Brazil, Madagascar, Namibia, Mozambique, Sri Lanka, South-West Africa and United States.
Rhodolite: II TOP II
It’s a variety of garnet. Rhodolite is available in deep pink or purplish-red colour and in United States, Tanzania, Zimbabwe and Sri Lanka.
Smoky Quartz: II TOP II
The smoky coloured variety of quartz group. The best known and most productive area is in the Swiss Alps where veins have yielded many tones of beautiful crystals. Other notable localities are in the Brazil, Madagascar, Russia, Switzerland, Ukraine and Scotland.
Spinel: II TOP II
Spinel was recognized as an individual mineral only 160-165 years ago. Before then it was classed as ruby. This gemstone is found in a wide range of colours and shades (colourless spinel being rare), of which the most valuable spinel is that which resembles in colour the red ruby. Spinel comes from Burma (Myanmar), Afghanistan, Sri Lanka & Thailand.
Tanzanite: II TOP II
The blue variety of zoisite discovered in Tanzania in 1967 is commonly known as tanzanite. In good quality the colour is ultramarine to sapphire blue; in artificial light, it appears more amethyst violet. When heated to 750-930 degrees F, the interfering yellowish and brown tints vanish and the blue deepens.
Tiger’s-Eye: II TOP II
A variety of cat’s eye quartz that has originated from crocidolite- a fibrous variety of asbestos, which has partially changed its original greenish-blue colour, by oxidation of the iron pigment, into golden yellow before replacement by quartz. It has a silky luster. Notable localities are India, Australia, Burma, South Africa, Namibia and United States.
Topaz: II TOP II
Formerly, the name topaz was not applied consistently or specifically; one called all yellow & golden-brown and sometimes also green gemstones topaz. The name topaz is most probably derived from an island in the Red Sea, now Zabargad but formally Topazos, the ancient source of peridot. Colours of the gemstone that called topaz are rarely vivid. The most common colour is tallow with a red tint; the most valuable is pink to reddish-orange. Other ranges of colours are pale blue, pale green, pink, golden-brown and sherry-brown. Topaz is very hard but has strong cleavage and breaks easily.
Tourmaline: II TOP II
The name tourmaline is adopted from the Sinhalese word “Turamali” which means mixed coloured stones. Normally this terminology is applied to gems whose identity is disputed. However, the usage of this name has not spread wide. Tourmaline is found in differentiated dikes of silica-rich intrusive rocks and is quite common around granite, where pegmatitic, pneumatolytic mineralizations are abundant. According to colour, many varieties are in trade; like 1) Achroite: colourless or slight coloured variety, quit rare, 2) Dravite: Yellow-brown to dark brown, 3) Indigolite: blue in all shades, 4) Rubelite: pink to red, also with violet tint, ruby colour is most valuable, 5) Schorl: Black coloured & vary common variety. 6) Siderite: lilac to violet blue, 7) Verdelite: green in all shades. Tourmaline is widely distributed,, the black tourmaline is of no value as a gem. The most deposits are in Russia, Sri Lanka, Burma, Brazil, Afghanistan, Zimbabwe, Namibia and Tanzania.
Turquoise (Froza): II TOP II
The name turquoise means “Turkish stone”, because the trade route that brought it  to Europe used to come via Turkey. Iron and Copper are the essential components in the chemical composition of turquoise. The iron gives the greenish tone to the gem while the copper imparts the blue body colour. Pure blue colour is rare, mostly turquoise is interspersed with brown, dark gray or black veins of other minerals or the host rocks. The popular sky-blue colour changes at 250 degrees C into a dull green, when soldering be careful for. This material is deposit near the surface by circulating the ground waters that carry copper, aluminum and phosphorous separated from the earlier rocks. Thus turquoise is a secondary mineral. These deposits however are not thick enough to produce thick rocks. It is occasionally found in the alluvial deposits. Being porous it weathers easily on the exposed surfaces. The mines of turquoise are in Iran, Brazil, Australia, Israel, Tanzania, United States, China and Mexico.
Synthetic Stones: II TOP II
An artificial man-made stones used in the same manner as a natural gemstone. There is nothing against the law in producing imitation or synthetic gems, as long as no one is harmed or defrauded by it. These products are indeed an important element of the gem trade. Those who do not want the security risk of, or cannot afford, genuine gems can use these for their adornment. Many gem minerals have been synthesized in the laboratory, often only in crystals to small to be cut or not of gem quality. Today many synthetic gemstones are mass produced. Some man-made stones have no counterparts in nature and so are not strictly synthetic stones but rather are oddities; however, they are generally considered as synthetic gems except when presented to imitate a natural gemstone, in which case they are considered a stimulant. Synthetic stones are usually sold by size in millimeter, rather than by weight. |
