Tabasheer (also spelled tabashir) or pearl opal is an organic stone that
forms in damaged joints (nodes) of bamboo plants. This hydrated form of
silica appears as a rounded mass of opal, and looks like seed pearls.
The table is the large, flat area at the top of a cut gemstone.
The size of the table of a cut gemstone in proportion to the girdle obtained
by dividing the table width by the girdle width
Tahitian pearls (also called black pearls) are dark-colored pearls. They
are produced by the large, black-lipped pearl oyster Pinctada margaritifera
(also called the Tahitian black pearl oyster), a mollusk found in the
tropical Indo-Pacific Ocean. Black pearls come in many colors, including
many body shades and overtone tints including gray (light gray to almost
black), peacock green (especially valuable), aubergine (eggplant), and
deep brown. The color of the dark nacre is determined by the minerals
in the oyster's diet (plankton) and in its environment. Many "black
pearls" are dyed or irridiated to enhance or change their color;
it is difficult to tell a natural pearl from a treated pearl. Tahitian
pearls are graded on six factors: 1.Shape (round is most valued), 2.Size
(the larger the better), 3.Surface Quality (clean is superior to blemished),
4.Luster (the more high-gloss luster the better), 5.Nacre Thickness (thicker
is better and longer lasting), and 6.Color (overtones atop the body color
add value to the pearl; the most sought-after color is peacock green and
darker colors are more valuable - overtone colors include blue, pink,
gold, silver, aubergine, and peacock green).
A stone, ring, charm or other object marked or engraved with signs or
characters that is believed to possess magical powers to protect the wearer
from harm. Also, see amulet.
A rare, very hard, heavy, gray metallic element that is exceptionally
resistant to corrosion and chemical attack below 150°C. It is used
to make light-bulb filaments, electrolytic capacitors, lightning arresters,
nuclear reactor parts, and some surgical instruments.
Tanvorite is a trademarked name for a manmade gemstone. This synthetic
stone is a deep blue-purple stone that resembles tanzanite.
Tanzanite (strontium-rich Calcium-aluminum silicate) is a valuable, transparent,
blue-violet type of zoisite resembling sapphire. Tanzanite has a hardness
of 6 and a specific gravity of 3.35. It is often heat-treated in order
to produce a deeper blue-violet color. This mineral was discovered in
1967 by Manuel d'Souza (an Indian tailor) southwest of Mt. Kilimanjaro
in Tanzania, Africa. Tanzanite is one of December's birthstones.
A small gemstone cut in a trapezoid shape with one end narrower than the
A dulled luster or finish caused by a thin deposit of a dirt which discolors
the surface of metal and is easily removed. Also a reaction between metals
and other chemicals which discolors the surface, particularly silver which
reacts with sulfur. The silver sulfide can be removed with a proprietary
cleaning product and gentle abrasion.
A bundle of threads bound at one end and loosely hung as an ornament.
Tavorite is a green to greenish-yellow to yellow gemstone. This vitreous
(glassy) stone, a Lithium Iron Phosphate, has a hardness of 5 and a density
of 3.28 (tavorite belongs to the Amblygonite Group, phosphates that have
a triclinic crystalline structure). Tavorite was named in 1955 by the
mineralogists M. L. Lindberg & W. T. Pecoria for the Brazilian mineralogist
Elysairio Tavora (1911- ). The chemical formula for tavorite is LiFe3+(PO4)(OH).
The streak is light green. Tavorite is found in Brazil, Germany, Portugal,
and USA (South Dakota and New Hampshire).
Taxco is a town in the State of Guerrero in Mexico, that is famous for
its silver jewelry production. The American silversmith William Spratling,
set up shop in Taxco in 1929, and many other silversmiths followed. Early
Taxco jewelry is avidly collected. Modern pieces are distinguished by
a registration mark of two letters followed by a series of numbers (this
mark was required by the Mexican government since 1979).
To temper is to strengthen or harden metal (or glass) by heating it or
by heating then cooling it. Harder tempers are stronger, more spring-like,
and brittler (when they are bent, they may break). Softer tempers are
weaker but bend easily.
A cut out pattern used to trace a design; like a stencil.
A tennis bracelet is a simple, flexible, in-line diamond bracelet. The
name tennis bracelet was first used when the great tennis player Chris
Evert dropped a diamond bracelet during a tennis match in the summer of
1987 (at the US Open Tennis Tournament). She had to stop the match until
she found her bracelet. Since then, that style of bracelet has been called
a tennis bracelet.
A style similar to a tennis bracelet with individually set stones linked
together in a chain, but not necessarily of uniform size or color.
Thermoluminescent minerals emit bright light when heated. For example,
chlorophane is a varity of fluorite that emits bright green light when
Thermoset plastic (also known as thermoplastic) is a hard, non-rigid synthetic
substance that cannot be melted by reheating. Thermoset plastic is formed
under high heat or pressure by a process known as polycondensation. Bakelite
is a thermoset plastic. The bangle above is "butterscotch" bakelite.
A lady’s hair ornament worn on formal occasions that curves with
the natural line of the head.
A tie bar is a piece of men's jewelry used to secure a necktie. A tie
bar usually has a decorative, bar-shaped front, and a clip on the back
that grasps the two parts of the tie.
A tie tack is a piece of men's jewelry used to secure a necktie. A tie
tack has a decorative front, and a pin on the back that goes through both
layers of the tie. Attached to the reverse of the pin is a chain with
a bar that is meant to go throught a buttonhole to secure the tie loosely
to the shirt.
The Tiffany setting is a ring with a high, six-pronged solitaire diamond
on a simple circular band. This design was introduced by Tiffany &
Co. in 1886.
Tiger's eye is a yellowish-brown to reddish-brown gemstone that has a
silky luster. This gemstone has bands of yellow and brown; when viewed
from the opposite direction, the colors are reversed. Tiger's eye is usually
highly polished and set as a cabochon (or cut as a bead) to display the
stone's chatoyancy (light reflected in thin bands within the stone). Tiger's
eye is a type of chatoyant quartz with fibrous inclusions (especially
crocidolite). This stone is sometimes heat-treated. Tiger's eye has a
hardness of 7.0. Most tiger's eye is mined in South Africa, but it is
also found in Australia, Brazil, Burma (Myanmar), India, Namibia, Sri
Lanka (Ceylon), and the USA. Green-grey varieties of this stones are called
cat's-eye quartz. Blue-grey to bluish varieties are called hawk's-eye.
Deep brown varieties of this stone are called bull's-eye or ox-eye.
A toggle clasp (also called a bar and ring clasp) is a jewelry fastener
in which a bar can be inserted into a ring to fasten a piece of jewelry.
It is used to attach the two ends of a necklace or bracelet.
Topaz (aluminum silicate fluoride hydroxide) is a very hard gemstone that
ranges in color from brown, to yellow to blue to pink. Pink topaz is usually
created by irradiating common yellow topaz. Other colors are often created
by heat-treating and/or irradiating topaz. Imperial topaz is golden orange-yellow
topaz; it is the most valuable topaz Topaz has a hardness of 8 and a specific
gravity of 3.5-3.6. Topaz may have been named for the legendary Topasos
Island in the Red Sea.
A torque (also spelled torc) is a necklace that consists of a narrow,
twisted band made of metal. This type of ornament was worn by the ancient
Celts, Britons, and Gauls.
A torsade is a necklace made of many strands that are twisted together.
Tortoise shell is the shell of a tortoise. It was used in the 1800's for
jewelry, hair combs, and other ornaments but is banned today. Tortoise
shell inlaid with precious metals is called pique. Tortoise shell will
burn easily, and smells like burning hair. It is easily imitated by plastic,
but its smell when burnt is very different. Tortoise shell has a hardness
of 2.5 and a specific gravity of 1.29.
Tourmaline is a dichroic gemstone that comes in many, many different colors;
it also appears to have different colors depending on the angle at which
it is seen. Tourmaline has the greatest color range of any gemstone -
the lighter colors are more valuable than the darker colors. It ranges
in color from pink to green to red (rubellite) to purple to blue-green
(indicolite) to colorless (achroite) to black. Watermelon tourmaline is
both pink and green. Tourmaline occurs as an elongate three-sided prism
and is mined in Brazil, The Ural mountains in Russia, Namibia, Sri Lanka,
and California. Tourmaline was only discovered in the 1700's. Tourmaline
has a hardness of 7-7.5 and a specific gravity of 3.02-3.25. It is doubly-refractive.
Tourmalinated quartz is a variety of transparent quartz that has needle-like
inclusions of black to dark green tourmaline crystals. This beautiful
stone is found worldwide. Tourmalinated quartz has a hardness of 7.0.
This stone is not enhanced.
Translucent materials allow light to pass through them, but the light
is diffused (scattered). Some translucent stones include moonstones, opals,
and carnelian. Lucite and other plastics can also be translucent.
Transparent materials allow light to pass through them without diffusing
(scattering) the light. Some translucent stones include diamond, zircon,
emerald, rock crystal, and ruby. Plastics like lucite can also be transparent.
In the confetti lucite bangle above, the glitter within the lucite is
Transvaal jade is not jade; it is a green to gray massive variety of grossular
garnet, calcium-aluminum silicate. It is found about 40 miles west of
Pretoria, South Africa. Transvaal jade can be distinguished from jadeite
or nephrite by its high refractive index. Grossular garnet has a refractive
index of 1.72 to 1.73, a hardness of 6-7.5 and a specific gravity of 3.5
Trapiche emeralds are rare, valuable emeralds that have a black, six-rayed
star within them, caused by black carbon impurities (the star is not an
asterism). These stones are usually cabochon cut to display the beautiful
spoke-like star. These stones are only mined in Colombia, South America.
Trapiche emeralds are sometimes called star emeralds (but the term star
emerald can also refer to emeralds with an asterism). Trapiche is a Spanish
word for the spoked wheel that is used to grind sugar cane.
Trap rock is a type of igneous rock. This solidified lava often contains
pockets of crystals.
A process by which the pore spaces of the stone are filled with a transparent
substance such as mineral oil, paraffin, or plastic to improve the color,
and make it more desirable.
A trembler is a piece of jewelry that has a part (or parts) set on a spring;
the spring-set parts move as the wearer of the jewelry moves.
Trifari is a pre-eminent jewelry manufacturing company that produces high-quality
and beautifully-designed pieces. The company began as Trifari and Trifari
in 1910, founded by Gustavo Trifari and his uncle; a few years later,
his uncle left and the company was simply Trifari. Leo Krussman joined
Trifari in 1917. In 1918, when Carl Fishel joined the company, they renamed
the company Trifari, Krussman and Fishel (their hallmark was T.F.K.).
Alfred Philippe, who had been a jewelry designer for Cartier and Van Cleef
& Arpels, designed pieces for Trifari for many years. Some other Trifari
designers included Jean Paris (1958 -1965), Lucius Passavanti (from about
1955 to 1968), Andre Boeut (1967 - 1979), and Diane Love (1971 - 1974).
Trifari was owned by the Hallmark Company from 1975-1988, and by Crystal
Brands from 1988-1994. It was then part of the Chase Capital division
of the Monet Group, which later went bankrupt and was bought by Liz Claiborne
(2000). The classic pin and earrings set above has paste rubies, emeralds,
sapphires, and diamonds (and was designed by Alfred Philippe, about 1947-8).
The trillion cut is a triangular cut based upon a brilliant style cut
(and not a stepped facet). The corners of the triangle are truncated (cut
short) and there are a variety of facets, giving this cut a sparkling
A triplet is a manufactured stone that is made by sandwiching three thin
layers of stones together. For example, an opal triplet had a top, protective
layer of clear quartz, a thin middle layer of opal, and a base layer of
dark, color-enhancing matrix (usually black onyx or ironstone).
Precious metals (like gold, platinum, and silver) are measured in troy
weight, which has units of pennyweights, ounces, and pounds. Troy ounces
and pounds are different from everyday US measures.
Tsavorite is a rare, deep green variety of grossular garnet, a type of
garnet, calcium-aluminum silicate. The emerald green color comes from
vanadium and chromium. Tsavorite is similar to emerald, but is rarer and
more durable; it also has a higher refractive index, 1.74. Tsavorite stones
over two carats are considered large and are very rare. Tsavorite has
a hardness of 7.5 and a specific gravity of 3.6. Tsavorite is found in
east Africa; it was named by Harry B. Platt of Tiffany & Co. for the
Tsavo National Park in Kenya, where this gemstone was originally found
in 1967. Tsavorite is not enhanced.
Tumbled stones were finished in a tumbler, a mechanical device that smooths
and rounds the surfaces of stones. Tumbled stones look very much like
stones that have been in a fast-flowing river or stream for a long time.
A tumbler is a rotating cylinder (powered by a motor) that smooths and
rounds the surfaces of stones, increasing their luster. As the stones
tumble around the cylinder, they bump against each other and smooth each
A non-translucent, porous semi-precious stone (it is a hydrated phosphate
of copper and aluminum) that is usually cut as a cabochon. Turquoise was
believed to have been first found in Turkey, hence its name (Turquie is
the French word for Turkey). The oldest turquoise mines are located in
Alimersai Mountain in Persia (Iran) and in the Sinai Peninsula in Egypt.
Turquoise is found in desert regions worldwide. The finest turquoise is
Persian (Iranian) turquoise; it is robin's egg blue and has no matrix
(streaks of the mother stone from which they were found). North American
turquoise is greener and has a matrix streaks. Over the years, oil from
your skin is absorbed by the stone and it will change color slightly.
Turquoise has a hardness of 6 and a specific gravity of 2.60-2.85. Turquoise
is the national gemstone of Iran. Turquoise is one of December's birthstones
Twinning is a common error in crystalization in which two crystals grow
out of one another or next to one another, and their crystal lattice is
oriented differently from one another (some twins are like a mirror image
of each other). If the crystals have grown into one another, they are
called penetrant twins (forming a cross-shape like Staurolite, a star-shape
like Muscovite, and other unusual shapes). If the crystals are mirror
images that grow next to one another, they are called contact twins (they
are often likened to Siamese twins). Twinning can drastically change the
outward symmetry of the mineral specimen, by either increasing or decreasing
the symmetry (like with spinel). For example, twinning can make an orthorhombic
crystal appear to be hexagonal (as in Aragonite).