A gem, usually deep red, of several varieties, including
the almandite and pyrope. When cut en cabochon garnets are called
Garnet is found in nearly all colors but blue. Rarest of garnets
is the green demantoid, found only in the Ural Mountains. Others
come from Brazil, India, Sri Lanka, and the United States.
A transparent violet-to-purple quartz. Believed by the ancient
Greeks to prevent intoxication.
Amethysts were used in both Greek and Roman jewelry.
Under certain conditions the color of some amethysts may be improved
by heating. Under other conditions heating may turn them yellow,
then clear. Found in quantity in southern Brazil and northern
Uruguay. Smaller amounts come from India, Sri Lanka, and Madagascar.
Transparent sea-blue or sea-green beryl; of the same family as
the emerald but far less valuable. Found in many parts of the
world, particularly Brazil, Sri Lanka, India, and Madagascar,
and in Maine, New Hampshire, Connecticut, and North Carolina.
An aquamarine crystal found in Brazil in 1910 weighed about 240
pounds (110 kilograms).
Pure crystallized carbon, the most highly esteemed of all gemstones.
The fiery brilliance of the diamond has made it the world's favorite
jewel. The word comes from the Greek term adamas, which
means "unconquerable." The diamond is the hardest natural substance
found on Earth. Diamond-tipped industrial tools can cut through
granite as easily as a steel saw cuts through wood. Diamonds are
crystals of pure carbon that have been subjected to tremendous
pressure and heat. This process is believed to have taken place
deep in the Earth. About Diamonds
A deep-green brilliant emerald is one of the costliest of gems.
The emerald is a variety of beryl. The finest stones
come from Colombia. Other sources are Brazil, Egypt, Australia,
Austria, Norway, and North Carolina.
Pearls can be black, brown, gray, rose, red, blue, green, purple,
yellow, and white. No one knows exactly how pearls develop their
color, since one oyster may produce pearls of several different
hues simultaneously. The most valuable pearls are white and silvery-white
saltwater pearls that form in the genus Pinctada. Black-lipped
oysters from the South Pacific Ocean and the Gulf of Mexico sometimes
produce naturally black pearls. Although natural pearls are found
all over the world, most of the natural pearls now harvested come
from the Persian Gulf, Sri Lanka, the Red Sea, and the Philippines.
Smaller quantities come from the coast of Venezuela and from the
Gulf of California. The cultured-pearl industry thrives in the
seas of Japan and off the northwest coast of Australia, where
few natural pearls are harvested. Japan produces more cultured
pearls than any other country. Most cultured pearls are produced
in underwater farms, with the mollusks suspended at the right
depth in baskets. Historically, Japanese women divers, called
ama, gathered the wild oysters.
A transparent red corundum valued according to shade of color.
Large rubies are often worth more than fine diamonds of the same
size. Pigeon-blood (deep carmine-red) rubies, which seldom exceed
three carats, are obtained from Myanmar. Darker rubies come from
Thailand. Rubies also occur in Sri Lanka, Afghanistan, and North
A yellowish green olivine. Found in St. John's Island (Red Sea),
Australia, Arizona, Hawaii, and, rarely, other places.
A transparent corundum, or aluminum oxide. Sapphires range from
white through blue, violet, yellow, and green to near black. Blue
star sapphires with six rays are favorite stones.
Fine sapphires are equal in value to diamonds of equal size. Found
in Myanmar, Thailand, Sri Lanka, and Jammu and Kashmir.
A complex aluminum borosilicate occurring
in great variety-colorless, rose red, green, blue, yellowish,
green, honey yellow, violet, and dark blue. Most tourmaline is
obtained from Brazil, Elba, Madagascar, and Maine, Connecticut,
An aluminum fluosilicate occurring in tawny yellow, blue, green,
reddish violet, pink, and colorless varieties. Found in Brazil,
Siberia, Sri Lanka, and the United States.
A zirconium silicate usually occurring in brownish, gray, or brownish
red varieties, but sometimes in yellows and greens. Colorless and
blue varieties are usually produced by heating brown zircons. Zircons
come chiefly from Sri Lanka and Indochina.