There are so many different gemstones that come in various colors and variations that it would be hard not to find one to suit your specific taste. Learning a bit about each gemstone and its basic properties will help you in your search for the perfect stone.
Alexandrite
Alexandrite is a variety of chrysoberyl. Named after Czar Alexander II, it is a color change stone that is green in daylight and light red in artificial light. Mined in Sri Lanka, Rhodesia, Brazil, Burma, Tasmania and the U.S., Alexandrite is quite rare and is barely ever used in modern jewelry. What is most famous about this stone is that it has the ability to change color. This unique characteristic makes Alexandrite one of the most valuable gemstones of all. It is also a very expensive stone. On Mohs'' scale of hardness, Alexandrite is 8.5.
Amethyst
Amethyst is the most highly valued and recognizable gemstone of the quartz family. Its affordable pricing makes it a perennially popular choice. It is found in a range of colors from violet to pale red-violet. Its primary sources include Brazil (Rio Granda, Para), Madagascar, Zambia, Uruguay, Burma (Myanmar), India, Canada, Mexico, Namibia, Russia, Sri Lanka and the United States (Arizona). On Mohs'' scale of hardness, amethyst is 7.
Aquamarine
Aquamarine is a member of the beryl family and ranges in color from an almost colorless pale blue to blue-green or teal. The most prized color is a deep-blue aqua color. It is 7.5-8 on the Mohs' scale of hardness and gets its name from Latin words meaning water and sea. The most valuable aquamarines come from Brazil, but it is also mined in Kenya and Nigeria, Madagascar, Zambia, Tanzania, Sri Lanka, Pakistan, Afghanistan and Russia.
Blue Topaz
Citrine
Citrine is a quartz crystal. While its name refers to a lemon yellow color, citrine can be found in a range of yellows from light yellow to dark yellow and golden brown. On Mohs'' scale of hardness, citrine is 7. Sources include Brazil, Madagascar, the United States, Argentina, Burma (Myanmar), Namibia, Russia, Scotland and Spain.
Citrines are a beautiful stone that is trying to make a comeback in the jewelry world.
Emerald
Emerald is the most precious member of the beryl family. Emeralds have an intense, rich and radiant green color. The name Emerald is derived from the French "esmeraude? and the Greek root "smaragdos? which means 'green gemstone'. In emeralds, inclusions are tolerated since they are such a fine gemstone. A high quality emerald has the potential to be worth more than even a diamond. It has a vitreous luster and sources include Colombia, Zimbabwe, South Africa, Russia (Urals), Afghanistan, Australia (New South Wales, Western Australia), Ghana, India, Madagascar, Malawi, Mozambique, Namibia, Nigeria, Pakistan, Zambia, Tanzania, and the United States (North Carolina). On Mohs'' scale of hardness, emerald is 7.5-8. The rich radiance of the emerald makes it such a unique gemstone; however, finding an emerald with good quality is hard because inclusions have an affect on the color. But, even an emerald with inclusions can be more valuable than an almost flawless emerald because the color has the potential to be deeper than the pale color of a flawless emerald.
Garnet
Garnets usually come in a deep red variation that is very pleasing to the eye. Garnets refer to more than ten different gemstones that have a similar chemical composition. Although red is the color most often that garnets come in, there are also sometimes variations of green, yellow, orange and earthy tones. Rhodolite is a purplish red; hessonite is the name for an orange, cinnamon, or pinkish variety. Tsavorite is the name given to dark green grossularite. Uvarovite and demantoid are also green varieties. The color of a garnet tends to change when seen during daylight or artificial light, therefore making them even more sought after. Mohs'' scale of hardness, garnet is 6.5-7.5 Garnets have excellent wearing qualities as a result of their hardness. Garnets come mostly from African countries, but also from India, Russia and Central and South America.
Lab Created Gemstones
Lab created gemstones are made of the same mineral composition as natural gemstones, and are created in laboratories with equipment that simulates the high pressures and heat that nature used to create the real gemstones far beneath the surface of the earth. A lab created gemstone is identical to the natural gemstone it replicates in every way; color, hardness, composition, luster, looks etc. The only difference between a lab created gemstone and a natural gemstone is that the natural gemstone most likely has flaws called inclusions, and lab created gemstones have no inclusions, as the mineral composition, heat, and pressure are controlled in the laboratory. Having no inclusions in a perfect lab created gemstone sounds favorable, however too perfect can sometimes look unnatural or phony. Chatham lab grown synthetic gemstones are not imitations. The Chatham created gemstone is identical to its natural counterpart. Only by careful examination under high power magnification can a trained gemologist separate the natural gemstone from the Chatham lab grown synthetic gemstone. *We indicate in our descriptions if the gemstone is a Chatham stone now you can get top quality, top color gemstones for a fraction of the price of natural gemstones.
Opal
Opal is a unique gemstone with a beautiful play-of-color display. It can exhibit a full range of hues from the color wheel set against a light or dark background. On Mohs'' scale of hardness, opal is 5.5-6.5. Primary sources include Australia, Brazil, Guatemala, Honduras, Indonesia, Japan, Mexico, Russia, Nevada and Idaho.
Almost 95% of opals come from Australia. The group of opals contains a number of different gemstones, which share one characteristic; they all shine and sparkle in a forever changing play of colors. While there are many different types of opal, the three most popular are black opal, white opal and fire opal. Black opal is the rarest, most expensive and considered by many the most beautiful. Since opals are not very hard, they need a protective setting and should be worn as often as possible because humidity and air help the stone last.
Onyx
Onyx is chalcedony quartz that is mined in Brazil, India, California and Uruguay. It has a fine texture and black color; however some onyx also display white bands or ribbons against a black or brown background and this variety is known as sardonyx.
Other varieties of onyx come in white, reddish brown, brown and banded. A variety of onyx that is reddish brown with white and lighter reddish bands is known as sardonyx. It is a 6.5 on the Mohs' scale of hardness. Onyx is a very good stone for use in carving.
Peridot
The Peridot reflects a variety of green hues, from dark leek green to a lighter yellow green. Peridot is a gemstone variety of chrysolite that varies in color depending upon the balance of iron and magnesium within the stone. The dominant source of peridot today is Arizona, with other significant deposits in Myanmar, Brazil, Australia, Norway and Africa. Peridot is the gem variety of olivine and ranges between 6.5 and 7 on the Mohs' scale of hardness.
Pink Sapphire
When people think of a sapphire, they often conjure up images of deep bluish tones. However, sapphires come in many different colors. The most valuable fancy sapphire color is the pink sapphire. Pink sapphire's come in different shades, there are orange pink and pinkish orange. Sapphires are a 9 on the Moh's scale of hardness. We will learn more about sapphires in the sapphire section.
Ruby
Ruby is a gemstone in the corundum family. It exhibits a range of red colors, and the most desired color is pigeon's blood (pure red with a hint of blue). The red in rubies comes from the presence of chromium, and the occasional brownish hues come from the presence of iron. On Moh's scale of hardness, ruby is 9. Rubies are sourced in Burma (Myanmar), Thailand, Sri Lanka, Tanzania, Afghanistan, Cambodia, Kenya, Madagascar, and Vietnam.
Sapphire
While sapphire and ruby are both corundum, they are distinguished by color. All red corundum is ruby. Everything else is sapphire. Sapphires posses the deepest blue color that comes in so many different shades and tones, such as yellow, pink, orange and purple. The most noted for the color blue, cornflower blue in particular. Sapphires have beauty, magnificence, transparency, and durability. The sapphire is a 9 on Mohs'' scale of gemstone hardness; sapphires are second only to diamonds in hardness. Sapphires other than blue are often referred to as fancy sapphire. While there is a wide range of color, the most popular colors include padparadscha (a light to medium toned, orange pink), pink sapphire and orange sapphires. Sapphires are only found in a handful of places throughout the world, such as India, Burma, Ceylon, Thailand, Vietnam, Australia, Brazil and Africa. A sapphire's value depends of the size, color and transparency of the stone.
Smoky Quartz
Smokey Quartz is a variety of chalcedony or microcrystalline quartz with a hardness rating of 7. Very similar to agate, and treated agate is often sold as black onyx. Onyx may be brown, white, grey, or black. Quartz is such a versatile stone, and also one of the most popular. Quartz comes in many varieties and tends to be very affordable. It has become known as the chameleon of gemstones and as the ?rock crystal? which was used in ancient times to make crystal balls. Smoky quartz is a brown transparent quartz variation that is normally used for unusual cuts.
Tanzanite
Tanzanite is a variety of zoisite. It has naturally occurring shades of blue, green, yellow, pink, brown and khaki but virtually all gemstone quality crystals are heat treated to produce the highly valued shades of sapphire blue, amethyst and blue violet. On Mohs'' scale of hardness, tanzanite is 6.5-7. Tanzanite is found in Tanzania near Arusha. Tanzanite is a brittle stone and although it can be worn daily, care should be taken to protect it from knocks, pressure and extreme temperature changes.
Tourmaline
Tourmaline is a fascinating mineral that can actually exhibit two or more colors in one crystal. It possesses one of the widest color ranges, reproducing every conceivable color in the universe. On Mohs'' scale of hardness, tourmaline is 7.5. It is vitreous on crystal surfaces, and because of that the polished stones will have a beautiful brilliance. Tourmalines are mined everywhere in the world including Africa, Afghanistan, Africa, Australia, Brazil, Kenya, Madagascar, Mozambique, Nigeria, Pakistan, Siberia, Sri Lanka, Tanzania, the USA, and Zimbabwe.
Topaz
A very hard and lovely mineral that has been known and valued both in ancient and modern times. Topaz naturally comes in yellow, brown, red, pink, and colorless varieties, but is also available in modern times in several shades of blue through treatment with irradiation. Topaz can be found in Brazil, Sri Lanka, Pakistan and Russia. Topaz is a very hard gemstone, an 8 on the Mohs' scale of hardness; it can be split with a single blow and should be protected from hard knocks.
Topaz has become a quite exotic stone and is sometimes confused with the quartz topaz, but topaz in its pure form is quite beautiful and exotic.
Diamond
The diamond, one of the four precious gemstones, is the hardest known material on Mohs scale of mineral hardness. This means it has an extraordinary resistance to being scratched by other materials other than another diamond. Because of the durable quality of diamonds, they are popular for wedding and engagement rings.
Cultured Pearls
Not to be mixed with pearls found in nature, cultured pearls are organically created in a controlled environment.
Turquoise
Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue.
Quartz
Quartz is one of earth's most common minerals. It's colors range from colorless to black. Amethyst and Citrine gemstones are just two of the many varieties of quartz. Quartz is the second most abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2.
Jade
Jade can come in a variety of colors like green, pink, or brown. In Ancient Chinese dynasties, it was used a decorative piece and was known as the "imperial gem". Jade is an ornamental rock. The term jade is applied to two different metamorphic rocks that are made up of different silicate minerals.
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Gemstones
There are three primary types of gemstone products:
Natural gemstones occur in nature and can be rare and expensive.
Laboratory-created stones — which also are referred to as synthetic, laboratory-grown, or manufacturer-created — have the same chemical, physical, and visual properties as natural gemstones, but they aren’t as rare and often are less expensive than natural gemstones with similar characteristics.
Imitation stones look like natural stones, but may be made of glass, plastic, or other less costly material.
Laboratory-created and imitation stones should be clearly identified as such.
Size
Gemstones may be measured by weight, size, or both. The basic unit for weighing gemstones is the carat, which is equal to one-fifth of a gram. Carats are divided into 100 units, called points. For example, a half-carat gemstone would weigh .50 carats or 50 points. When gemstones are measured by dimensions, the size often is expressed in millimeters (for example, 7x5 millimeters).
Treatments and Enhancements
Gemstone treatments or enhancements refer to the way some stones are treated to improve their appearance or durability, or even change their color. The effects of some treatments may lessen or change over time, and some treated stones may require special care. Some enhancements affect the value of a stone when measured against a comparable untreated stone.
A jeweler should tell you whether the gemstone you’re looking at has been treated:
if the treatment isn’t permanent
if the treated stone requires special care
if the treatment significantly affects the value of the gemstone
Here are some common treatments and their effects:
Heating can lighten, darken, or change the color of some gemstones, or improve a stone’s clarity.
Irradiation can add color to colored diamonds, certain other gemstones, and pearls.
Impregnating some gemstones with colorless oils, wax, or resins hides a variety of imperfections to improve the stones’ clarity and appearance.
Fracture filling hides cracks in gemstones through an injection of colorless plastic or glass to improve the stones’ appearance and durability.
Diffusion treatment adds color to the surface of colorless gemstones; the center of the stone remains colorless.
Dyeing adds color and improves color uniformity in some gemstones and pearls.
Bleaching lightens and whitens some gemstones, including jade and pearls.
Diamonds
A diamond’s value is based on four criteria:
Color often is graded on a scale established by the Gemological Institute of America (GIA). On the GIA scales, color is rated from D to Z, with D at the top.
Cut refers to the quality of how the diamond has been shaped, taking into account the diamond’s proportions, polish, and symmetry.
Clarity measures the natural imperfections in the stone. On the GIA scales, clarity is rated from flawless to I3. A diamond can be described as “flawless” only if it has no visible surface or internal imperfections when viewed under 10-power magnification by a skilled diamond grader.
Carat refers to the stone’s weight.
Diamond weight usually is stated in carats and may be described in decimal or fractional parts of a carat. If the weight is given in decimal parts of a carat, the figure should be accurate to the last decimal place. For example, ”.30 carat” could represent a diamond that weighs between .295 and .304 carat. Some retailers describe diamond weight in fractions, using the fraction to represent a range of weights. A diamond described as 1/2 carat could weigh between .47 and .54 carat. If diamond weight is stated as fractional parts of a carat, the retailer should disclose two things: that the weight is not exact the reasonable range of weight for each fraction or the weight tolerance being used.
Treatments
Some diamonds, like other gemstones, may be treated to improve their appearance. Since these treatments improve the clarity of the diamond, some jewelers refer to them as clarity enhancement.
Fracture filling, for example, conceals cracks in diamonds by filling them with a foreign substance. This filling may not be permanent, and jewelers should tell you if the diamond you’re considering has been fracture-filled.
Lasering is a treatment that involves the use of a laser beam to improve the appearance of diamonds that have black inclusions or spots. A laser beam is aimed at the inclusion; acid is forced through the tiny tunnel made by the laser beam to remove the inclusion. Lasering is permanent,
and a laser-drilled stone usually does not require special care. While a laser-drilled diamond may appear as beautiful as a comparable untreated stone, it may not be as valuable. That’s because an untreated stone of the same quality is rarer. Jewelers should tell you whether the diamond you’re considering has been laser-drilled.
Imitation diamonds, such as cubic zirconia, resemble diamonds in appearance but cost much less. Certain laboratory-created gemstones like moissanite resemble diamonds and may not be adequately detected by the instruments originally used to identify cubic zirconia. Ask your jeweler if he has the current testing equipment to distinguish between diamonds and lab-created stones.
Pearls
Pearls can be natural, cultured, or imitation.
Natural pearls are made by oysters and other mollusks.
Cultured pearls also are grown by mollusks, but with human intervention: an irritant introduced into the shells causes a pearl to grow.
Imitation pearls are man-made with glass, plastic, or organic materials.
Natural pearls are very rare, so most pearls used in jewelry are either cultured or imitation pearls. Cultured pearls usually are more expensive than imitation pearls. A cultured pearl’s value generally is based on its size, usually stated in millimeters, and the quality of its nacre coating, which gives it luster.
Some pearls occur naturally in black, bronze, gold, purple, blue, and orange tints.
