Types of Diamond

A rare mineral Boracite was first discovered in Luneburg, Hanover, Germany in 1789. The mineral occurs in white to colorless as well as bluish, greenish, grey and yellowish colour.Formed from Magnesium Borate Chloride (Mg3B7O13Cl), the name Boracite comes from the fact that the mineral contains a high content of Boron. It ranks 7 – 7.5 on the Moh’s Scale of hardness and has a Specific Gravity of approximately 2.9 – 3.0. Crystals of Boracite are vitreous, transparent to translucent and occur in a variety of forms. It is also slightly soluble in water.

Boracite is commonly found in marine evaporite environments, which provide the right factors needed for the mineral to form. Boracite is commonly found in association with other evaporite minerals like Anhydrite, Gypsum, Hilgardite, Magnesite and Halite. Its crystals are typically embedded in these other evaporite minerals or vice versa.

Notable amount of Boracite is found in Yorkshire, England; Strassfurt, Germany; France; Bolivia; Chactaw Salt Dome, Louisiana and Otis, California, USA. A variety of Boracite found at Strassfurt, Germany is a fibrous form and is named Strassfurtite, after the locality.

Boracite is easily identified by its crystal habit, color, associations, locality and its high hardness. In industrial applications, Boracite is used as an ore of boron for boric acid and borax (a cleaning agent and useful industrial chemical). Although it has nice color, clarity and the hardness necessary to be used as a gemstone, Boracite is rarely cut for this purpose, because it is slightly soluble in water and ordinary wear dulls its surface. Still, it is a very attractive mineral specimen among collectors.

Citrine is one of the accepted birthstones for November, as well as the anniversary gemstone for the 13th year of marriage. Found mainly in Brazil, Citrine appears naturally but most commercial form is the result of heating amethyst. Colors range from pale yellow to yellowish-brown and “Madeira” red (the color of wine). As Amethyst is heated to turn its color to gold colored Citrine, jewellery made from this stone should be kept away from prolonged exposure to strong light or heat.
Readily available and affordable in large sizes, Citrine can be used for daily wear. Citrine earrings, necklaces and rings are popular as it is one of the most versatile of gems. Citrine can be easily confused with topaz and has even been called “topaz quartz.”

The hardest, rarest, densest natural substance known to man, Diamonds have been a source of fascination since 800 BC. In those days the Indians believed that diamonds were created when lightning struck rock and the sub-continent was the only producer of diamonds for an astounding 2,500 years. As bewitching as diamonds are they have produced more than their fair share of myths over the centuries.Diamonds were not cut until the 14th century and it wasn’t until 1725 that deposits were discovered in Brazil and 1866 that the South African storehouse was unearthed. While Africa is known as the Diamond continent, it is actually in Australia that the largest reserves are found – including the very rare and highly valued pink and red fancy colored diamonds.

Diamonds are made of pure carbon atoms that exist deep in the ground, exposed to intense heat and pressure over billions of years. Over time, this pressure builds up and forces the diamonds and rocks up toward the surface in a volcanic-like explosion. The explosion creates a very deep, wide hole called a “kimberlite pipe” into which most of the diamonds settle. These “pipes” resemble gigantic carrots encrusted with diamonds. It can take years to fully excavate an entire pipe.

Some amazing attributes of Diamonds are:
· their age – the first diamond deposits were brought to the surface of the earth approximately 2.5 billion years ago while the most recent deposits are roughly 50 million years old;
· their hardness – diamonds are so hard that they can only be polished by other diamonds;
· rarity – more than 250 tons of ore need to be blasted, crushed and processed to yield one carat of rough diamond and of that rough, only 20% is suitable for gem cutting;
· density – diamond is so dense that it actually slows down light to less than half its normal speed;
· fluorescence – 30-40% of diamonds glow blue when exposed to ultraviolet light and some will even glow green, yellow, white or (extremely rare) red.

Celebrated in song, diamond jewellery, has long reigned as the ultimate statement of ardor and affection and is found to be the most intimate of gifts.

A rare mineral, Ekanite was discovered in 1953 in Sri Lanka and was described as a new type of gemstone. In 1961, it was announced as a new metamict mineral. Today, gem-quality Ekanite is occasionally found at Eheliyageda in Sri Lanka.

Ekanite is another of several minerals that occur in a beautiful green color.

A beautiful green colored mineral, Ekanite is a radioactive, but non-hazardous, mineral composed of calcium sodium potassium thorium silicate (ThCa2Si8O20). It ranks 6 – 6.5 on the Moh’s hardness scale with a Refractive Index of 1.57 and a Specific Gravity of 3.3. Crystals of Ekanite are translucent and vitreous. Apart from the typical green, it also occurs in yellow and dark red colors.

Ekanite specimens from Sri Lanka sometimes reveal a weak four-rayed star, but this phenomena is quite rare. The star form of Ekanite is considered one of the rarest gemstones available on the market today. In 1985 a beautiful 161.04 carat Ekanite cabochon displaying a unique eight-rayed star was found and cut in Sri Lanka. It is considered to be a one-of-a-kind specimen.

Ekanite is also found in Mt St. Hilaire and Rouville Co., Quebec, Canada and at several locations in Siberia, Russia: Yakutia, Aldan Shield Torgo river basin, Davan and Murun massif.

Ekanite is a very rare type that is not widely known to the general public. As rarer stones are more highly prized than more common varieties, Ekanite specimens can command quite high prices on the market; especially those with vivid green coloring and nice luster.

Fluorite is known as the “Most Colorful Mineral in the World” due to its absolute chameleon like ability to appear in different colors. The most popular color for Fluorite is a deep purple, which can rival Amethyst in its finest examples. This clearly indicates that color cannot be relied upon as a gemstone test.

Common Fluorite colors include: Purple, blue, green, yellow, colorless, brown, pink, black, reddish orange and more. Some of the most eye-catching examples are multi-color Fluorites with distinctive bands and zoning. The word “fluorescent” comes from the mineral Fluorite which commonly fluoresces blue and has been known to glow yellow, green, red, white or purple. Some Fluorites even display different colors under longwave and shortwave UV light.

Chemically, Fluorite is Calcium Fluoride (CaF2) with a Hardness of 4 and a Specific Gravity of 3.0-3.3, and is available all around the world including: Brazil, Canada, China, England, Germany, Italy, Mexico, Norway, Russia, Switzerland, USA and more.

As Fluorite comes in a variety of colors the worth of any piece is determined by an individual. Fluorite is highly sought after as it is a relatively soft stone with a glassy luster. Though gem quality specimens achieve greater prices than those favored by mineral collectors, it is an inexpensive stone; thus making it the second most popular mineral amongst collectors after quartz.

Grossular Garnets appear in many colors: colorless, yellow, orange and green to exceptional pink. The most popular color is the medium dark green variety, known as Tsavorite, named after the Tsavo National Park on the border of Tanzania and Kenya, where it was discovered. Tsavorite ranges from light green to very dark and the finest stones are clean with an intense medium green color.

Garnets date back to the Bronze Age (i.e. more than 5,000 years ago), when it was a very popular gemstone. The name “Garnet” is believed to have derived from “pomegranate” with its red, Garnet colored seeds. Unlike other gemstones, Garnets are believed to contain both protective and destructive elements.

Garnets are a group of related minerals, containing cubic crystalline structure with slight variations in their chemical compositions. In all, there are 7 major types of Garnets, which include Almandine, Pyrope, Spessartine, Grossular, Andradite, Rhodolite and Malaia.

Though the different types of Garnets are made up of different chemical components they all share a Refractive Index of 1.72 – 1.94, Specific Gravity of 3.40 – 4.30 and Hardness of 6.5 – 7.5 on the Moh’s Scale. And are found around the world including: Kenya, Sri Lanka, Thailand, Brazil, India & Arizona (USA) in a wide range of warm colors such as reds, oranges, yellows and Burgundies, as well as greens and some rare color-change varieties.

As Garnets display a wide variety of colors, color becomes the most important characteristic while evaluating these stones. The color must be intense and uniform with a tone that is not too light or too dark. Fine Garnets should be eye clean with minimal inclusions under magnification. Size is also a very critical determinant of the stone’s value.

The yellow form of beryl, the “mother of gemstones” is known as Heliodor. It may also appear in yellow, yellow-green, orange and brown colors. However Heliodor does not include golden colors, as those are known as golden beryl.

Beryl occurs in a variety of colors, but only the transparent ones are used as gemstones. As pure beryl is colorless, the traces of the different impurities are responsible for this gemstone’s vast color range.
Some well-known colored gemstones that belong to the beryl group are emerald, morganite, goshenite, bixbite and aquamarine. Whereas the other forms of beryl are simply referred to by their color (i.e. golden beryl, red beryl etc.).

Heliodor has a hardness of 7.5 – 8, a refractive index of 1.57 – 1.60 and a hexagonal crystal system. They are available as both a faceted gem and as Heliodor Cats Eye. Beryl (Heliodor) is famous for its perfect, six-sided prismatic hexagon crystals that usually occur individually. Some well-crystallized 8-meter forms are also known to have existed.

Treating the stone with oil can mask the internal flaws in Heliodor and thus one must be cautious of dealers who often apply this treatment to a stone without informing the buyer. All varieties of Beryl, including Heliodor can be faceted into various gem cuts. Some stones even display cat’s eye effect when cut and polished. Transparent beryl such as Morganite and Heliodor are also carved sometimes into ornamental figures. Perfect, transparent, six-sided rough Heliodor crystals are also worn occasionally as pendants.

Heliodor is found in Madagascar, Brazil, Rangoon, Tien-Shan Mountains, Tajikistan, Middle Eastern countries, North Carolina and California in the U.S.

Indicolite or Indigolite is the beautiful greenish blue to hot blue variety of Elbaite, which is a part of the Tourmaline group. Considered as one of the most colorful member of the gemstone family, the Tourmaline group, sometimes have the same gems with alternating colors. The most popular variety of Tourmaline is Elbaite, which is found in many beautiful and varied colors. These are highly prized as both minerals and gemstones and range from transparent to translucent forms. The opaque variety however has little gem value.

Indicolite a rarer form of Elbaite, has a typical color which is deeper than other blue gems, almost neon blue. Other varieties are: the green colored Verdellite, a cat’s eye variety, pink to red colored Rubellite and green and red colored (in the same stone) Watermelon Tourmaline. When viewed from different angles, all Elbaite specimens show stronger or even different colors. This property causes the blue color in Indicolite to appear darker when viewed down the axis of an uncut crystal. Thus to take full advantage of the color potential of the stone, the gem cutter must be aware of this property.

Indicolite is a very good stone to be worn as it has a hardness of 7 to 7.5 on the Moh’s Scale. This gemstone mined in Madagascar, North America, Brazil, Myanmar, Africa, Siberia, Australia and Sri Lanka is now becoming very popular on the gemstone market due to its property of hardness.

Indicolite’s blue color is believed to have a soothing power and relieve stress; those born in October also wear it as a birthstone.

The Spanish referred to jade has – “piedras de ijada” – which meant “The stone of the loins” and it is from this colorful phrase that we derive the English name for this most unusual of gems. The term jade actually refers to two distinct types of stone, which closely resemble one another – the more common nephrite and the more expensive jadeite.

Jade was actually used by the Central American Mayan civilization hundreds of years before it attained a royal position in the Middle Kingdom. The Mayans mined jadeite in Guatemala making it into weapons and tools. The Chinese cult of Jade worship began in the Neolithic era when nephrite from the Kunlun Mountains was used in religious ceremonies, agriculture and war. The “Stone of Heaven” became so influential with the Chinese emperors that Confucius even wrote that men should aspire to its qualities of benevolence, intelligence, righteousness, humility, resonance, loyalty, faith, virtue and truth.

Jade is harder than granite and is also very difficult to carve than solid steel. When diamonds were first introduced to China sometime between 1005 and 221 BC, they were originally more highly valued as jade carving tools than as gems. Although Jade has long been associated with the Chinese culture it wasn’t until l784 that Burmese jadeite found its way there and superseded the local nephrite as the imperial stone.

The Maoris in New Zealand also used nephrite weapons. The fibrous structure of nephrite is very densely packed making it the “super skull crusher” gemstone. In spite of its low hardness, it is considered to be the toughest gem material.

Jade is believed to bring good luck, health and fortune, assist during childbirth and protect infants from disease. Throughout Asia millions wear jade amulets believing that they give the owner power, knowledge, pure thoughts, long life and immortality.

Intensity of color and transparency are the most important factors in judging quality. While jade is never fully transparent, the closer it gets to transparency, the higher it is valued. The most highly valued colors are the very rare “Imperial” green and apple green. Lavender jade is also very rare and attains high prices. A green swirl of jade in an otherwise white stone is known in Chinese as “moss in snow” and fetches princely sums.

There are two distinct types of Jade – jadeite and nephrite. Nephrite is found in scattered areas around the globe and appears in a wide variety of colors. Jadeite predominantly comes from Burma and while it is available in gray, yellow, pink, blue, lavender, red, white, brown and black, it is most popular in the classic green that most people associate with the stone.

Kunzite

Discovered in 1902, Kunzite was named after G F Kunz, the chief gemologist of Tiffany’s and a noted mineralogist of the time. Known as the ‘evening stone’, Kunzite is the pink variety of Spodumene, while the green variety of the stone is known as Hiddenite. Kunzite exhibits pleochroism, that is there is quite a color variation when the crystal is seen either from the top or bottom. And because of its strong pleochroism, cleavage and splintery fracture, it is considered to be a real challenge to a gem cutter. However its lovely pink to violet color makes Kunzite a very attractive and desirable gemstone.

As it is a pastel gem, it shows its color well in larger sizes. Made up of lithium aluminum silicate (LiAl (Si2O6)) the lithium in Kunzite’s chemical composition gives it the beautiful pink-violet color. As this stone can fade in high heat or direct sunlight, it is best worn in the evening – thus earning the nickname ‘Evening Stone’.

The astrological signs for Kunzite are Scorpio, Taurus & Leo and this stone is believed to promote peace and purification and is considered excellent for meditation.

A fragile stone with a hardness of 6 – 7 on the Moh’s scale this stone is mined in Afghanistan, Brazil, Burma, Canada, Madagascar, Malagasy Republic, Mexico, Pakistan, Russia, Sweden and the United States.

Labradorite a dull gray-black stone attains its charm from a superficial play of colors known as labradorescence. It also comes in a golden yellow transparent form that makes some stunning gem-quality stones.

Composed of Calcium Sodium Aluminum Silicate [Ca(50-70%) Na(50-30%) (Al, Si)AlSi2 O8], Labradorite has a Refractive Index of 1.55 – 1.75, Specific Gravity of 2.7 – 2.74 and a hardness of 6 – 6.5 on the Moh’s scale. Thus making Labradorite a versatile and wearable gem.

Available in brilliant pastels and deep gold colors Labradorite makes for a truly outstanding gem, perfect for anytime the wearer wishes to brighten the mood. Transparent Labradorite is fine, clear and relatively free from inclusions. Shades vary from an almost lime-yellow color to bright canary yellows and golden tones. While looking at the gray-black colored form of the stone one must look for the intensity of schiller on the surface when viewed from different angles. Thus resulting in different colors being visible from different angles or a range of colors visible at the same time.

Discovered in Labrador-Canada, Labradorite is also found in China and the Scandinavian Peninsula.
As it is a rare gem type, the prices of these stones vary widely depending on their availability and quality. Also because of the variety of color shades this stone is available in, one should choose a color one feels comfortable with. And it is ideal for people who like large stones in bright colors.

Known as the “honey stone” Mellite is a rare mineral favored by both collectors and gem-lovers. Discovered in 1793 in the town of Arten, Thuringe, in Allemagne of France, the name Mellite was derived from the ancient Latin word for “honey” which is “mellitus” due to its appearance in natural honey color. Though white specimens of Mellite are occasionally discovered and brown to reddish shades are unearthed, it is usually found in a honey to waxy yellow color.

Mellite Al2[C6(COO)6]•16(H2O), is a mellitate of alumina. It has a Refractive Index of 1.51 to 1.53 and has a hardness of 2.0 to 2.5 on the Moh’s Scale of Hardness. This mineral has been found in France (region of Seine), in Germany (Thüringen, Arten), in Hungary (Csordakut, Tatabanya, Sordakuit Banya) and in Russia (Malevka, Malowka, Tula)

Found in deposits of brown coal its formation is partly the result of vegetable decomposition, a highly unusual situation amongst gemstones.

Occurring in brown, golden brown, green and nearly black colors, Nuummit has a hardness of 5 – 6 and a Specific Gravity of 2.8. A foliated metamorphic rock, Nuummit is composed of Magnesium, Iron, Silicon, Oxygen and Hydrogen (Mg,Fe)7Si8O22(OH)2 and is approximately 3.8 billion years old, thus making it extremely unique.

Nuummit also occurs in extremely small amounts in Spain and southwest of Douglas, Converse County, Wyoming, USA.

The Romans had been wearing opals for centuries and considered them a symbol of hope and purity while for the early Greeks they embodied the powers of foresight and prophecy. The more fancifully minded Arabs thought that opals must have fallen from heaven in flashes of lightning thus achieving their unique play of color or “opalescence”. Amazingly this opal escence is a result of the 5-10% of water trapped inside the stone in which rows and rows of tiny spheres of silicon dioxide are arranged, diffracting light in a unique fashion to form wide spectrum of colors.

The official stones for those born in October are Opal and tourmaline. The physical structure of opal is unique. Tiny spheres of silicon dioxide form a pyramid shaped grid interspersed with water. Tiny natural faults in this grid cause the characteristic “play of color”. The effect is similar to the rainbow colors displayed on a soap bubble, only that this is even more dramatic.
White Opals are commonly found and they vary widely in body color. Black is considered the most valuable as it accentuates the play of color. Fire opal like the yellow, orange or red, is often faceted and can resemble ruby. The rare of them all are the green and blue Opal.

The combination of body color and play of color, we are faced with infinite possibilities. So, pricing becomes very crucial and is very complex. Size is also a factor with the carat price for larger stones accelerating accordingly. The intensity of the play of color and the extent to which it covers the opal’s surface also count.

Opal is occasionally cut with pieces of matrix – the host rock. This strengthens the opal and can also lend a more interesting appearance. The finest examples are Boulder Opal, which sometimes have an undulating surface of “hills” and “valleys”. As opal is relatively soft and fragile it is often made into doublets or triplets – backed with plain black opal and fronted with clear quartz. These are ideal for opal rings or any piece that is likely to be receiving rough treatment.

The oldest known gem, Pearl was considered the most valuable stone for centuries and there have been plenty of legends surrounding it (Krishna’s wedding gift to his daughter, Cleopatra’s love potion etc.). The first known source of pearls was the Persian Gulf and the oldest known pearl jewellery is a necklace found in the sarcophagus of a Persian princess who died in 520 BC.

This gem especially enamored the Romans. And it was believed that pearls were a symbol of the moon and had magical powers. The Chinese also used pearls to cure heart trouble, indigestion, fever, bleeding and eye ailments and till today use it as a skin whitener and as a cosmetic product. In India pearls were believed to give peace of mind and strength to the soul. Europeans too believed that whole or powdered pearls cured matters of the mind and heart.

Generally worn as strings, pearl rings too are gaining popularity nowadays especially those with unusual black colored pearls.

Queen Isabella funded Christopher Columbus’ expedition to discover the new world, which also led to the discovery of pearls in Central American waters. This led to a flood of American pearls in the European market. However greed for these sea gems resulted in the depletion of the American pearl oyster populations by the 17th Century.

Then in 1919, a Japanese perfected and patented the art of cultivating pearls; thus turning production of pearls into an industry by itself. A Natural pearl or Oriental pearl forms, when an irritant enters into a particular species of mollusk. As a defense mechanism the mollusk secretes a fluid to cover this irritant. Layers of this coating, also known as nacre is deposited onto the irritant until a pearl is formed.

A similar process is used to create a cultured pearl. However in this process the irritant is an artificially implanted mother-of-pearl bead or nuclei. As long as there are enough layers of nacre deposited on the nucleus to result in a beautiful pearl, the size of the nucleus is of little importance.

Almost every pearl that is sold these days is cultured. And you are likely to come across “Natural” pearls only at auction houses. As they symbolize purity and innocence, pearls are considered as ideal wedding gifts. In the western hemisphere pearls are given as gifts to couples celebrating their 3rd and 30th wedding anniversaries.

Saltwater pearls are more expensive than freshwater pearls. The Akova Japanese pearls are the most popular. However, freshwater pearls are available in a wider range of colors than saltwater, including purple, violet, orange, blue and gray. Freshwater pearls are cheaper to produce as each mollusk can yield up to 30 pearls. The American freshwater pearls are allowed to mature for longer periods as compared to other cultured pearls thus forming thicker nacre, which gives these pearls an unusually high luster.

As pearls are available in a variety of colors, it is best to choose the color that complements you. While buying pearls check them under different light sources and make sure that the luster is uniform throughout the surface. Being porous they will soak up any substance that they will come in contact with, especially perfume, cosmetics and sweat, so make sure to wipe them clean after every use.

Discovered on the Swedish island of Ut Arfvedson, by Jos Bonifácio de Andrada e Silva, a Brazilian scientist at the end of the 18th century, Petalite a rare mineral generally occurs in pastel yellow. The name is derived from the Greek word ‘Petalon’ meaning ‘leaf’ and ‘Lithos’ meaning ‘Stone’. It is commonly found in mass without any crystal form. However it does occur in crystals sometimes in the tabular or columnar prism form. These fine crystals are however rare and fragile; thus Petalite is seldom cut as a gemstone.

Petalite has been found in Brazil, Australia, Sweden, Finland, USA, Zimbabwe, Namibia and Elba in Italy. However Brazil and Namibia are the major sources of nice transparent stones. Composed of Lithium, Aluminium, Silicon and Oxygen (LiAlSi4O10), Petalite has a Specific Gravity of 2.4 and a relative hardness of 7 and is commonly found in Lithium-bearing pegmatite.

A unique mineral, Petalite occurs in some beautiful pastel colors. The large sized stones are greatly desired by collectors due to its rarity. A stone that weighs above 2.0 carats is considered large especially in case of Petalite.

Prehnite an attractive mineral with a very good luster forms in the cavities of basaltic rocks and along fractures of diabase rock. With a bright luminescent green coloring Prehnite is a hydrous, calcium-aluminum-silicate mineral, which can be facetted or carved into ornaments. Usually found in a pale green to a grass green color, Prehnite can also be gray, white or colorless; some specimens even resemble jade.

The first mineral to be named after a person – Dutch minerologist Colonel Hendrik von Prehn, Prehnite was discovered in Jurassic (Karoo) dolerite in the Cradock district of the Eastern Cape Province in the early 18th Century.

A calcium aluminum silicate hydroxide: Ca2 Al2 Si3 O10(OH)2, Prehnite has a hardness of 6 – 6.5 and a Specific Gravity of 2.9+. It is found in India, South Africa, France, Germany, New Zealand, Switzerland, Scotland and in New Jersey, Connecticut, Virginia, Pennsylvania, California, Colorado, Michigan in the US.

Believed to enhance one’s protective field and memory, Prehnite helps build the immune system and bring about peace and calm. Ideal for stress release, its color and unusual touch generates serenity and tranquility and is thus useful for curing anemia and blood disorders. It is also used as a Prediction stone by the Channellers and the Shaman’s.

A popular semi-precious stone, Pectolite occurs in white or colorless, gray, light yellow, light brown, light blue and light pink colors. Discovered in 1828 in Mont Baldo and Mont Monzoni, Italy, the name Pectolite comes from the Greek word ‘Pectos’ meaning ‘well put together’ in reference to the groups usually formed by the crystals of this mineral.

An ocean blue variety of Pectolite was discovered in the Dominican Republic a few decades ago and was given the name Larimar, which is quite popular in the semi-precious stone market.

Composed of NaCa2Si3O8(OH), Sodium Calcium Silicate Hydroxide, Pectolite, has a Specific Gravity of 2.7 – 2.9 and a hardness of 4.5 – 5 on the Moh’s Scale. The crystals are vitreous, transparent to translucent and occurs in fibrous tufts, globular masses and in radiating veins. Pectolite has been mined in Lake Country – California, Paterson and Franklin – New Jersey (USA), The Bahamas, Dominican Republic, Italy and England.

Pectolite can be confused with other similar looking minerals such as Okenite, Wollastonite, Artinite and some others. But it can be easily identified due to its association with Zeolites, as others do not form this association and by the way it occurs in basalt cavities.

Discovered in the nineteen seventies Larimar was named after the Dominican who had discovered the stone and is mined only on a unique Caribbean mountain and nowhere else in the world. It has an extraordinary blue color similar to that of the ocean in tropical areas.

Larimar, the pale blue to sky blue variety of Pectrolite, is quite attractive and popular among those who like polished jewellery. Found in the Bahamas and Dominican Republic, Larimar is similar to Turquoise in appearance. And like Turquoise it too is used in contemporary Native American jewellery.

Prasiolite is also known as Vermarine, and is quite simply Green Quartz. It is found in nearly every geological environment and is a component of almost every rock type. It is also the most varied in terms of varieties, colors and forms. Some macrocrystalline (large crystal) varieties are well known and popular as ornamental stones and as gemstones. These include: Amethyst, Citrine, Ametrine, Rose Quartz and Prasiolite.

Heating certain types of quartz in the presence of iron forms Prasiolite. Prasiolite is sometimes confused with Green Beryl, Peridot (olivine) and Tourmaline, all gem types that are considerably more expensive than Prasiolite. Prasiolite has a Refractive Index of 1.55 and Specific Gravity of 2.65, with hardness of 7 on the Moh’s Scale. Most commercial Prasiolite is found in Brazil and Arizona (USA).

The most important aspect to consider when purchasing Prasiolite is the Intensity of color and clarity. Color variations from a pale yellow-green to deeper, more lustrous greens are available. A tough stone displaying beautiful colors, Prasiolite is ideal for everyday wear and, as an inexpensive gem variety, is perfect for a wide variety of applications and usage.

They are divided into two groups: the transparent crystalline varieties and the translucent to opaque chalcedonies that are microcrystalline forms of quartz. There are many different varieties in these two types but they have one thing in common: they are low in cost. Some are downright cheap! Quartz is one of the most abundant minerals on the earth’s crust.

The queen of the quartz, Amethyst is most expensive of the quartzes. Amethyst ranges from pale to dark violet. The finest qualities of Amethyst are a medium dark violet with a strong secondary red color. Darker shades of Amethyst may appear slightly differently under different light sources. Amethyst is available in all sizes and shapes. Light Amethyst will be very low in per carat prices with the finest qualities still well under US$l00 per carat. Darker Amethyst of any size will have color zoning. This may not be visible without extensive examination. Often the zoning consists of areas of red violet and areas of blue violet, this combination can enrich the appearance of the stone. Sometimes the zoning is easily visible and detracts from the beauty of the stone.

The bi-color variety, Ametrine is part Amethyst colored and part Citrine colored. It was first discovered in Bolivia. Generally Ametrine is cut into octagon or emerald cut shapes to emphasize the two colors. Ametrine has been carved into some very interesting gem art works. Prices will start in the low end and go to moderate price per carat.

The quartz without color, also called “rock crystal” simply lacks interest as a jewellery stone. Even when it is well cut it lacks brilliance. Occasionally it will contain some interesting inclusions that can increase its appeal. Colorless quartz is occasionally found with rutile needles inside, which look like long golden threads, sometimes arranged in a pattern. This is called Rutilated Quartz and is popular in art jewellery. Most gold bearing quartz is milky white rather than transparent.

Smoky quartz is brown transparent quartz of all shades; it generally has a slightly grayish cast. Prices should always be very inexpensive.

Quartz can be made into beads and have been popular for a hundred or so years; these are often faceted into appealing shapes. Tiger’s eye is quartz with asbestos inclusions; this gives it a subtle silky appearance. Generally it is golden to brown in color; it can also be dyed. Blue material is called Crocidolite. Star quartz is a fascinating stone; the quartz may be colorless or pink. The stars are six-rayed and roll around the stone as it is moved.

Occurring in a range of colors from very pale pink, pale to deep red, orange red, brownish red, orange-brown, pale to dark brown and black, Rhodochrosite has become a mineral of interest of late. The name is derived from the Greek words ‘Rhodon’ meaning ‘Rose’ and ‘Chroma’ meaning ‘Color’ due to its famous rose color. There are also banded varieties of this stone available; stones with pink – white and with pink – red bands, which are extremely attractive and are used in semi-precious jewellery.

A manganese carbonate mineral (MnCO3), Rhodochrosite is a soft stone, ranking only 3.5 – 4 on the Moh’s Scale of Hardness and has a Specific Gravity of around 3.5. It is commonly found in association with Calcite, Quartz and metal sulfides.

Rhodochrosite is found exclusively in the Sweet Home Mine in Alma and the Sunnyside Mine in Silverton, Colorado. And the Hotazel Mine in South Africa is famous for producing deep red clusters of Rhodochrosite crystals. However the mines most famous for producing Rhodochrosite are in the provinces of Catamarca and La Rioia in Argentina as they produce the most attractive pink and red-banded variety of Rhodochrosite, which are also occasionally referred to as ‘Inca Rose’ and used as an ornamental stone.

Rhodochrosites are often used to make figurines and the tubular forms are often cut into circles with concentric bands, which are unique. Rhodochrosite jewellery is truly unique and beautiful due to its famous rose color.

A sedimentary rock consisting of cemented grains of quartz, Sandstone is actually named after the sand-sized grains of the quartz. Commonly found in gray, buff, red or brown colors, Sandstone is formed deep within the ground under great amount of heat and pressure, which transforms small grains into a tough rock with tightly packed minerals.

The cementing material in sandstone is usually calcium carbonate, silica or iron oxide. As there are plenty of varieties of Sandstone available in the market, they are differentiated on the basis of their variations in color, hardness and texture, which in turn depends on the cementing material. Those which contain iron oxide are red to reddish brown in color, while those with silica or calcite as the binding material will be light in color, usually pale yellow, buff, or white. And green Sandstone in addition to sand and glauconite, often contains fossil shells and iron oxides.

A common mineral found in the earth’s crust, Sandstone is available in large quantities in association with most other sedimentary rocks. Sandstone can be crushed to form loose sand grains, which can be then used in construction and in other industries as sand. Due to the variety of colors and textures sandstone is available in, it enjoys a place in the semi-precious stone market also. It is also used extensively in carvings and cut into spheres or oval forms.

Tanzanite is the most popular gemstone today after Diamond, Ruby, Sapphire and Emerald. Believed to be discovered by the Masai tribe in the Merelani hills in Tanzania, this stone was noticed first by a Portuguese geologist, named DeSouza, who traveled to Tanzania and noticed these magnificent blue stones and helped Tiffany & Co. in introducing this stone to the world. With vast amounts found in the northern part of the country near the Merelani hills, Tanzania has become the main commercial source of Tanzanite. Though small amounts have been found in Kenya it was not considered large enough for commercial purposes until recently.

Tanzanite has a hardness of 6 – 7 on the Moh’s scale, thus ultrasonic should never be used to clean this gemstone, as it is quite fragile. However there are Tanzanite rings, earrings and necklaces that are available in the market that enhance the personality of the wearer.

Zoisite, the greenish to brownish color mineral when heated to 600 degrees Celsius, undergoes an amazing metamorphosis, resulting in this vibrant blue to blue violet gemstone – Tanzanite. Though initially only small stones were available, today larger stones are also seen in the market. The value of these stones mainly depends on the color of these gemstones, which display an amazing blue during daytime and a violet shade under bright light. Thus the gemstone, which has the minimum violet color even when viewed under bright light commands a high value. Since flawless Tanzanite crystals are easily found, the stone should not contain many inclusions.

Named after Monsieur Valium, a French explorer, Villiaumite was discovered in 1908 in a collection of rocks from the Islands of Los in French Guinea. Considered as an extremely rare mineral till 1982, Villiaumite has been found more frequently in recent times in sodalite xenoliths (inclusions) in Nepheline Syenite composite rocks.

Nepheline – Syenite, a medium to coarse grained, light to medium gray colored igneous rock is predominantly composed of a silicate mineral called orthoclase (KAlSi3O8). Minerals that are found in Nepheline – Syenite generally occur embedded in massive sodalite or may be in small randomly distributed, irregular shaped cavities not more than 1 cm in dimension.

Xenoliths occur in Nepheline – Syenite which are fine-grained, dense, dark gray to brownish gray and are significantly different from most Nepheline – Syenite found, in terms of their appearance and texture. Sodalite xenoliths have so far produced the largest number of minerals in the growing list of minerals in recent times. Villiaumite is one such mineral found and added to the list.

Villiaumite occurs in colors ranging from pale orange-red to very deep carmine red. With hardness similar to that of an average fingernail that is 2 – 2.5 on the Moh’s Scale and a Specific Gravity of 2.8, Villiaumite is transparent and has a glassy luster.

Composed of approximately 54.75% of Sodium and 45.25% of Fluoride (NaF, Sodium Fluorine), Villiaumite has anhedral to subhedral crystal structure. Commonly associated with Amphiboles, Calcite, Eudialyte, Fluorite, Nepheline, Pectolite and various other minerals from the sodalite xenolith environments, Villiaumite can be easily distinguished from other minerals because of their color and crystal forming habit.

Zircon’s popularity began to grow in the sixth century, when Italian artisans featured the stone in jewellery designs. The brilliance of zircon has captured the hearts of those who set their eyes on this magnificent gemstone. During the Middle Ages, zircon was believed to contain remedial power, protecting the wearer from diseases and banishing insomnia. The name “zircon” is derived from the Arabic words, “zar”, meaning gold, and “gun”, meaning color.

The two major suppliers of Zircon are Thailand and Cambodia, apart from Vietnam, Burma, Sri Lanka and Africa that supply these marvelous gemstones to the world market. There are three natural types of zircons: low, medium and high. The variance is due mainly to the differences in the specific gravity and refractive index. Having the highest refractive index among any natural gemstones, with the exception of diamonds, the brilliance of high zircon is second to none. Its refractive index is purely dependent on the temperature.

Despite its brilliance, Zircon is quite brittle and can easily be chipped or scratched. A unique characteristic of zircon is that the light splits into two rays as it passes through the stone. As a result, the back facets appear as double images. They are often blue or colorless. Some of the other color varieties are yellow, orange, green, and brown. The intensity of color and clarity is the most important criteria and any presence of flaws diminishes its value.