Table: The large, flat, top facet
of a cut gemstone
located in the center of the crown.
Table-cut: See Emerald
Cut.
Table Percentage: The size of the table
of a cut gemstone
in proportion to the girdle
obtained by dividing the table width by the
girdle width.
Tantalum: 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.
Tanzanite: A variety of zoisite
named after its country of origin, Tanzania, where it was first
discovered in 1967 and is still the only place where it can be
found. Tanzanite is popular for its brilliance
and is known for its varying shades of violet; from deep rich
purple to lilac. The gem
can be heated to achieve the most sought after shade, a vibrant
blue violet. Good quality tanzanite is usually faceted,
but the rare pieces that have flaws are simply made into cabochons.
Tapered baguette: A small gemstone
cut in a trapezoid shape with
one end narrower than the opposite end.
Tarnish: 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.
Tassel: A bundle of threads bound
at one end and loosely hung as an ornament.
Taxco: (TAHKS' coh) The center of
silversmithing in Mexico. Silver
produced there up until about 1970 is considered collectible. In
1979 the government began to require silversmiths to stamp a
registration mark consisting of two letters and several numbers.
Tea caddy: A decorative box created
for storing tea leaves. Many have two compartments; one for
black tea and the other for green tea. Some of the finest tea
caddies were created in England and crafted of exotic woods
adorned with tortoise shell, ivory
and mother of pearl.
Template: A cut out pattern
used to trace a design; like a stencil.
Tennis bracelet: A bracelet
made up of individually set gemstones
of uniform size and color linked together like a chain
so it is somewhat flexible.
Tennis-style: A style similar to a tennis
bracelet with individually set stones linked together in a chain,
but not necessarily of uniform size or color.
Tessarae: Pieces of stone,
glass, or ceramic tile that are mounted in mortar to make a mosaic.
See also: Micromosaics.
Three-stone diamond ring: A ring
bearing three diamonds of
the same shape representing the past, present and future of a
relationship. The center stone is usually slightly larger than
the other two.
Tiara: A lady’s hair ornament
resembling a crown that does not form a complete circle.
Tie tac: A short pin with an
ornamental top or face that pins a tie to the shirt.
Tiffany Setting: A generally
round, high, six-prong setting
with long, slender prongs
that flare out from the base introduced by Tiffany & Co. in
1886. It is most commonly used today for large stones such as a diamond
solitaire.
Tiger Iron: A banded, opaque
stone, with metallic grey,
some red, and sometimes a little brown Tiger's
eye.
Tiger's Eye: A semiprecious
variety of quartz found in
South Africa. It may be yellowish-brown, bluish, or red in color
with bands of darker and lighter shades across its surface. It
has a silky luster, and
catches the light causing the chatoyant
quality.
Tin: A malleable, silvery metallic
element which is not easily
oxidized in the air, and so
is used chiefly to coat iron
to protect it from rusting. It is primarily extracted from the
ore cassiterite where it is found as an oxide.
Tin is malleable at ordinary temperatures, but brittle when
heated and is a part of numerous alloys
such as soft solder, pewter,
type metal, and bronze. It
is most commonly used in the form of tin foil
with mercury to form the reflective surface of mirrors.
Titanium: A metallic
element used in some jewelry
because of the range of colors it produces when heated.
Toe Ring: A type of body jewelry
worn around one or more toes. Toe rings come in styles similar
to rings worn on the fingers,
but toe rings have a small gap on the bottom of the ring to
allow them to slip over the tips of the toe more easily.
Toggle clasp: A means of
fastening two ends of a chain
together consisting of a ring on one end and a short bar on the
other. The bar is slid through the ring and sits across it so it
does not slide or pull.
Tone: How light or dark a stone
appears.
Tongue Bar: A bar shaped stud
worn through a hole pierced
in the tongue.
Topaz: A fluosilicate
of aluminum that occurs in
rhombohedral crystals
and is used as a gemstone.
Although it is a hard stone, topaz can be susceptible to
breaking. According to some, the name is from Topazos, a small
island in the Red Sea, where the Romans obtained a stone which
they called by this name, but which is now called chrysolite.
Topaz is sought after because it is lustrous,
has double refraction
and a strong hue. It may be
found in many colors, such as blue, brown, clear, green, orange,
pink, red, yellow, white. The most valuable topaz is
"Imperial" topaz with a golden yellow to orange color.
The most popular color is an enhanced blue treated with heat to
develop it into a rich “Tiffany” blue color which resembles aquamarine,
but is more affordable. Yellow quartz
is sometimes called topaz, but is considered "false
topaz". True topaz is said to be the symbol of love and
affection to act as a protector by making the wearer invisible
in emergencies. Topaz is the birthstone
for November.
Tortoise Shell: A mottled,
nutty brown shell material with a spotted, striped, or sometimes
even speckled pattern. Popular for 19th century jewelry
and hair combs, tortoise shell was banned and is no longer used
for these items. There are very close plastic imitations of
tortoiseshell. One technique to differentiate tortoise from its
imitators is to touch the surface with a hot pinpoint. Tortoise
will give off a smell like burning hair, while plastic will emit
an acrid chemical odor.
Total Depth Percentage: A measure
of the depth of a diamond
from the table to the culet
divided by the average diameter, (width), of the girdle.
The depth percentage of most diamonds
is between 53 and 63 percent.
Tourmaline: A complex
crystalline silicate
occurring usually in three-sided or six-sided prisms terminated
by rhombohedral or scalenohedral
planes containing aluminum,
boron, and other elements.
Black tourmaline (schorl) is the most common variety, but there
are also other varieties, as the blue (indicolite), red (rubellite),
also green, brown, and white. The red and green varieties when transparent
are valued as gems.
Tourmaline can be found in more colors than any other stone and
heat can also be applied to tourmalines to lighten, or enhance,
the existing hue of the gem.
Trachyte: A light gray igneous
rock with a rough surface consisting of orthoclase
feldspar.
Translucent: Allowing light
to pass through, but not transparent.
Transparent: A substance
that allows light to pass through it easily and objects placed
on the back can be fully seen through the substance.
Transvaal jade: See African
Jade.
Treated Turquoise: A process by
which the pores of the turquoise stone
are filled with a transparent
substance such as mineral oil, paraffin wax, or plastic to
improve the color and make it more desirable.
Tree Agate: A variety of chalcedony
quartz that is a very common
and used often in jewelry.
Tree agate is simply agate
with mottled green and/or brown patterns that resemble tree
foliage.
Tremolite: A white or pale
green mineral of the amphibole
group composed of calcium magnesium
silicate and used as a
form of asbestos. The compact variety of tremolite, called nephrite,
is a form of jade.
Triangle cut: See Trillion-cut.
Triclinic: Having three
unequal crystal axes intersecting at oblique angles
Trilliant: See Trillion-cut.
Trillion-cut: A brilliant-cut
gemstone that is
triangular in shape rather than round with 44 facets.
Troy Weight: gold
and silver are measured in
"Troy weight", from Troyes in France, a system that
includes pennyweights,
ounces and pounds. The ounces and pounds do not equal the
Avoirdupois or customary U.S. system that other common goods are
measured in. gold is also
commonly measured in metric grams. A pennyweight
(abbreviated dwt.) is equal to 1.5552 grams.
24 grains = 1 pennyweight
= 1.5552 grams
20 pennyweight = 1 troy
ounce = 31.1035 grams
12 ounces = 1 pound troy = 373.24 grams.
Tsavorite: A transparent
green garnet of the grossular
family of garnets found at
Tsavo, Kenya. Tsavorite is not the only green garnet,
see also Uvarovite.
Turquoise: A hydrous
aluminum phosphate
colored by copper salts
found in desert regions throughout the world and used in jewelry
by the natives who live there including Mongolian, Chinese,
Native Australian, Persian, and Southwestern Native American.
Different colors of turquoise, varying from sky blue to nearly
green occur in untreated turquoise. Brown or grey streaks in
turquoise are caused by the "matrix", or "mother
stone", from which the turquoise is mined. Interesting
matrix patterns are considered to add beauty to the stone. Only
Persian turquoise is usually without apparent matrix. Modern
turquoise stones that appear very shiny and absolutely flawless
are actually manufactured. Pulverized turquoise is reconstituted
with a plastic binding medium then cut
and shaped as though it were natural stone. This material is
generally avoided by collectors. Touching the stone leaves oils
on it which alters the color of the turquoise over many years.
Collectors tend to value these color nuances as "the patina
of time". This unique stone is usually cut
into cabochons, or domes,
to enhance the natural beauty of the gem.
Turquoise is considered a source of good fortune and beauty.
Turquoise, Treated: A process by which the pores of
the turquoise stone are filled with a transparent
substance such as mineral oil, paraffin wax, or plastic to
improve the color and make it more desirable.
