Natural Gemstones Description
Ruby (Corundum)-: Ruby- the name given to red, gem-quality corundum-is one of the best gemstones. Rubies may be in any shade of red, from pinkish to purplish or brownish red depending on the chromium or iron content of the stone. Frequent twining of the crystals makes the material liable to fracture, yet ruby is a tough mineral, second only to diamond in hardness.
Pearl-: Natural Pearl’s are formed in shell-fish- especially oysters and mussels- as a natural defense against an irritant such as piece of grit. Layer’s of aragonite, known as nacre, are secreted around the irritant and gradually built up forming the solid pearl.
An irritant is introduced to initiate the formation of a cultured pearl. In a “nucleated” cultured pearl a small bead is used as a nucleus upon which the layers of the nacre are secreted. There appears to be no major difference between natural and cultured pearls. Cultured pearls are more suited for wearing as there are fewer blemishes than natural pearls.
Topaz-: Topaz is a hydrous aluminum fluoro silicate that occurs typically in the veins and cavities of granite pegmatites, rhyolites, and quartz veins. The hardest silicate mineral and one of the hardest minerals, Topaz makes excellent mineral specimens because of its high luster, attractive colours, and well formed crystals. The name comes from the Greek topazion, which may originate from the Sanskrit Tapas, meaning “Fire”, or from the Egyptian Island of Topazos (now Zebirget or St. John’s Island) in the Red Sea. Topaz occurs in a range of different colours: deep golden yellow Topaz and pink Topaz are the most valuable.
Gomed (Hessonite)-: The orange version of Grossular Garnet, Hessonite is also sometimes known as “Cinnamon Stone” because of its distinctive brownish-orange colour. Hessonite derives its colour from iron and manganese content. Hessonite has been a popular stone for thousands of years since the times of Greeks and Romans. Hessonite is also an important stone in Vedic astrology. Known in Hindi as Gomedha, it is believed to have been formed from the fingernails of the great demon Vala, which were scattered among the lakes of the East.
Emerald (Vanadium Beryl)-: Renowned for its incomparable colour, the Emerald has been prized for millennia. The ancient Egyptians mined Emerald as early as 300 B.C from a source by the Red Sea that was later known as “Cleopatra’s Mines”. Emerald derives its beautiful green colour from the presence of chromium and vanadium. Emeralds are rarely flawless. Emeralds are found in granites, pegmatites, and schists, as well as alluvial deposits; the finest emeralds are from Columbia followed by Austria, India, Australia, Brazil, South Africa and U.S.A.
Diamond-: Diamond is the hardest mineral on earth, and this, combined with its exceptional luster and brilliant fire, has made it the most highly prized of all gems. Pure colourless Diamond is the most popular, but other varieties – yellow, green, pink, red, and black- are also found. Because of the uniform arrangement of their constituent carbon atoms, Diamond crystals are well formed – usually octahedral with rounded edges and slightly convex faces. Diamond forms at high temperatures and pressures 50 miles (80 km) or more underground. Diamonds are graded by the four C’s: colour, cut, clarity and carat (weight).
Cat’s Eye (Chrysoberyl)-: Chrysoberyl occurs in range of colours from green, greenish yellow, and yellow to brown. It is a hard durable stone. When cut well, the gems are brilliant but lack fire. Two varieties, alexandrite, cat’s eye have unique qualities of their own. Cat’s eye, when cut en cabochon, has a near white line across a yellowish grey stone, due to canal-or feather like fluid inclusions, needle like inclusions of rutile.
Blue Sapphire (Neelam)-: Any Corundum Gem that is not red in colour is called Sapphire, although popularly Sapphire is associated only with Blue stones. Sapphire gets its rich blue hue and unique “velvet” luster, caused by presence of minute inclusions, combined traces of titanium and iron. The prime colour is the fabled cornflower blue of sapphires from Kashmir. The most prized sapphires come from Kashmir.
Coral-: Coral is made by small and simple marine invertebrate animals such as the coral polyp, which is related to sea anemones. Their dense limestone (calcium carbonate) skeleton cluster together and build up over thousands of years into Coral reefs and Coral Islands. The surface of the Coral “branches’ has distinctive patterns made by the original animals- either striped or like wood grain. Most Corals are made of calcium carbonate. Most precious Coral is found in warm waters.
Alexandrite-: Alexandrite, a rare variety of chrysoberyl is prized for its remarkable optical properties. The very rare and valuable Alexandrite changes from green in daylight to red, mauve, or brown under incandescent light. An important source of Alexandrite was the Ural Mountains of Russia, where the variety was first described in 1830 by emerald miners on the birthday of Alexander II. Synthetic chrysoberyl, synthetic corundum, and synthetic spinel have all been produced to imitate alexandrite’s colour change.
Garnet-: Garnets are a large group of silicates that form under conditions of high temperature and/or pressure. The members of this group have a common crystal form and a degree of similarity in their chemical composition. It is usually opaque or subtranslucent, but the rare transparent stones have high luster.
Moonstone (Orthoclase)-: Moonstone is the opalescent variety of orthoclase, with a blue or white sheen or (shiller), rather like the shine of the Moon. This is caused by the reflection of light from the internal source made up of alternating layers of albite and orthoclase fledspar.
Amethyst-: Boasting the famed colour of royalty, Amethyst sets the colour standard for all other purple Gemstones. A variety of Quartz, Amethyst has long been prized and has been included in royal collections, ancient Egypt to the British crown jewels. It is a dichroic, showing a bluish or reddish purple tinge when viewed from different angles.
Jade-: Jade has been cherished for millennia by cultures as far apart as China and Central America and British Columbia and New Zealand. The lustrous green stone, stronger than steel has been used for tools and ornaments, and is highly believed to confer luck, health and spiritual well-being upon its owners. For centuries, Jade was thought to be a single Gemstone, but in 1863 two types were recognized; Jadeite and Nephrite.
Peridot-: Peridot has an olive - or bottle green colour that is due to presence of iron and a distinctive oily or greasy luster. Good quality crystals are very rare. The main source of Peridot in the ancient world was Topazos Island (now Zebirget or St. John’s Island)
Zircon-: Zircon is most famous for its colourless stones, which closely resembles Diamond. Zircon may be distinguished from Diamond by its double refraction and by wear and tear on its facet edges. Most Zircon contains radioactive thorium and uranium, which eventually breakdown the crystal structure. Zircon provides the wearer with wisdom, honour and riches.
Turquoise-: One of the first Gemstones to be mined Turquoise has long been prized for its intense colour which varies from sky blue to green depending upon the quantities of iron and copper within it. It is a secondary mineral formed under the influence of evaporating surface waters in typically arid regions.
Lapis Lazuli (Lazurite)-: It is blue rock made up of several different minerals including lazurite, sodalite, hauync, calcite, and pyrite. The composition of Lapis Lazuli varies, but it is the intense dark blue, with minor patches of white calcite and brassy yellow pyrite, that is considered to be the best quality. The best quality is from Afghanistan.
Aquamarine-: Aquamarine meaning “water of the Sea” is of sea green to sky blue variety. It is dichroic, appearing blue or colourless as the stone is viewed from different angles. Gem quality Aquamarine is found as hexagonal crystals.