Colored Gemstone Checklist
by Shawna Edwards
Published April 28, 2010 | Updated July 27, 2015
Emeralds, sapphires, and rubies -- these are perhaps the most beloved of colored gemstones. But many bright and enchanting gems are available to accessorize your personal style and fill your jewelry box. A gemstone is a mineral that is used to decorate items of value, usually jewelry, but also household items, and even clothing. Gem-quality minerals must be rare stones, which increases their value, with attractive color and enough durability to tolerate cutting and polishing. Learn more about gemstone jewelry with this checklist of popular gemstones.
Popular Colored Gemstones
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Known for its beauty and durability, this pale to dark violet gemstone wears very well in rings. The finest varieties of amethyst are medium-dark violet with a strong secondary red color. A variety of quartz, amethyst stones are usually heat-treated or irradiated to enhance their color. Brazil is the principal source of amethysts, but they are also mined in North America and Asia. Amethyst is the February birthstone.
From the same mineral family as emeralds, aquamarines range in color from pale blue and greenish blue to deep blue. Look for clarity and intensity of color to assess the value of this stone. As the size of aquamarines increases, their color tends to intensify. Brazil, Russia, and Nigeria are the world's major suppliers. Aquamarine is the March birthstone.
Chalcedony is a catch-all term for a number of agate-type gemstones, including carnelian, sard, bloodstone, onyx, sardonyx, chrysoprase, fire agate, and jasper. The name is applied more specifically to white, grey, blue, and brown varieties with a waxy translucent to transparent luster. Chalcedony is widely available throughout the world.
Sometimes confused with yellow topaz, citrine is somewhat more durable. It does appear naturally, but most commercial citrine results from heating amethysts, as they are both quartz stones. Colors range from pale yellow to yellowish brown and Madeira red. At one time, the Madeira shades were valued higher, but people today prefer the lemony shades. Look for clarity and attractive color in evaluating citrines. Brazil is the world's principal source for this gem. Citrine is one of the birthstones for November.
Green or bluish-green emerald is a form of beryl; its color comes from the presence of chromium or vanadium. The most important factor in assessing emeralds is rich, velvety, uniform color with a minimum of internal flaws (unflawed stones are very rare). Emeralds are often treated with oil or wax to enhance their color and durability. Colombia is the principal source of emeralds, but they're also mined in Zambia, Pakistan, and the United States. Emerald is the May birthstone.
Garnets are a group of related silica minerals with slight variations in their chemical compositions. Because of those variations, this gem comes in many colors. Among the major types, almandine garnets are the most common and have the red wine color that most people associate with this gemstone. Spessartine garnets are the orange to red-orange variety. Grossular garnets can be colorless, yellow, orange, green, or pink; the medium dark green variety known as tsavorite is the most sought-after. Rhodolite garnet is considered the "queen of garnets" due to its delicate pink to violet-red color. Garnet is the birthstone for January.
Legend has it that the Vikings used a thin slice of iolite as a lens to determine the exact position of the sun, helping them navigate safely from Europe to the Americas and back. Although the cut gem has a violet-blue color, several colors appear when the crystal is viewed from different directions; an iolite will appear a sapphire blue from one side, as clear as water from the other, and a honey yellow from the top. This characteristic makes cutting iolite especially difficult because the blue color is lost if the stone is not cut in exactly the right direction. Iolite is mined in India, Africa, and Brazil.
Moonstone is the most valuable variety of feldspar. It features a variety of colors, ranging from colorless to grey, brown, yellow, green, and pink. Clarity ranges from transparent to translucent in moonstones, and they're usually cut in smooth-domed cabochons to maximize their characteristic shimmer. The best moonstone is from Myanmar and Sri Lanka and has perfect clarity, a colorless body, and a blue sheen that reminds one of the moon. It was considered a sacred, healing stone in several ancient cultures, especially in India.
This form of chalcedony, with color produced by the presence of silicon dioxide, can be black and white to grey, or black and red to brownish red. The gem has a waxy appearance and is frequently used in cameos. Onyx is associated with the astrological sign of Capricorn.
This stone is best known for the rainbow of colors that flash through it as a result of the unique structure of silica dioxide crystals within. Opals are usually found with white backgrounds, but black, blue, or grey backgrounds occasionally appear. Australia is the world's primary producer of opals. They are also mined in Central Europe, Mexico, and Brazil.
Colored from pale lime to olive green, peridots have a velvety appearance, a rich glow, and a slightly oily luster. They are mined primarily in Egypt, the U.S., and Myanmar, but a new deposit of superior quality was found in Pakistan in recent years. Pay attention to the cut and clarity when assessing peridot. The purer green it is, the higher the value; tinges of brown lessen the value. Peridot is the August birthstone.
The rich, red hue of ruby makes it one of the most popular gems on the market. Rubies are the red variety of corundum, and color is the most important factor in assessing the value. Rubies should be as close to a true, spectral red as possible. Most rubies are mined in Asia with the best gems specifically found in Myanmar. Ruby is the July birthstone.
The most sought-after sapphires are cornflower blue, but they can also be pink, green, orange, and yellow. Sapphires are composed of corundum with the varying colors resulting from the presence of iron and titanium. Red corundum stones are rubies. Evenness of color is the significant factor in assessing sapphires, and they are often heated to permanently enhance their color. Sapphires are mined in Asia, the U.S., and Australia. Sapphire is the September birthstone.
In 1967, Tiffany & Co. caught the world's attention when it showcased this recently discovered African stone in its gemstone jewelry collection. Flawless tanzanite stones are fairly common, so it's important to choose a stone without too many inclusions. Tanzanite is a fragile gemstone; it should never be ultrasonically cleaned. Tanzania is the only commercial source of tanzanite. According to popular myth, a lightning strike caused a wildfire in the grasslands of the Merelani hills. When the Masai herders returned to the area, the magical blue stones appeared on the ground.
In colors including yellow, orange, red, pink, blue, and sherry brown, topaz has been used as a gemstone since the days of ancient Egypt. In the past, the orange (also known as imperial) and yellow varieties were most common, but the large supply of blue topaz available now makes it a popular and economical choice. Red and pink are the rarest colors. The world's largest supplier of topaz is Brazil, with Pakistan and Russia emerging as new sources. Yellow topaz is one of the birthstones for November, and blue topaz is the December birthstone.
Often described as the chameleon gemstone because it is found in all spectrums of color, tourmaline can resemble emerald, ruby, sapphire, or even appear as crystallized rainbows with several bands of color. It most often appears as a green or pink stone. The red variety is called rubellite because its vibrant color resembles the finest rubies. Color intensity and clarity of the gemstone are the most important factors in assessing tourmaline. Tourmaline is mined in Brazil, the U.S., Sri Lanka, and various parts of Africa.