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TABASHEER OPAL
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.
TABLE
The table is the
large, flat area at the top
of a cut gemstone.
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.
TAHITIAN PEARL
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).
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.
TANVORITE
Tanvorite is a trademarked
name for a manmade gemstone.
This synthetic stone is a
deep blue-purple stone that
resembles tanzanite.
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.
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.
TAVORITE
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
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).
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.
TEMPER
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.
TEMPLATE
A cut out pattern
used to trace a design; like
a stencil.
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.
TENNIS BRACELET
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.
TESSARAE
Pieces of stone,
glass, or ceramic tile that
are mounted in mortar to make
a mosaic. See also: Micromosaics.
THERMOLUMINESCENT
Thermoluminescent
minerals emit bright light
when heated. For example,
chlorophane is a varity of
fluorite that emits bright
green light when heated.
THERMOSET PLASTIC
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.
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 BAR
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.
TIE TAC
A short pin with
an ornamental top or face
that pins a tie to the shirt.
TIE TACK
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.
TIFFANY SETTING
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
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.
TIGER IRON
A banded, opaque
stone, with metallic grey,
some red, and sometimes a
little brown Tiger's eye.
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 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.
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.
TORQUE
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.
TORSADE
A torsade is a necklace
made of many strands that
are twisted together.
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
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 - thel ighter
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
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.
TRACHYTE
A light gray igneous
rock with a rough surface
consisting of orthoclase feldspar.
TRANDLUCENT
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.
TRANSLUCENT
Allowing light to
pass through, but not transparent.
TRANSPARENT
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 visible.
TRANSVALL JADE
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 - 3.67.
TRAPICHE EMERALD
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
Trap rock is a type
of igneous rock. This solidified
lava often contains pockets
of crystals.
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.
TREMBLER
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.
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
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 billiance.
TRICLINIC
Having three unequal
crystal axes intersecting
at oblique angles
TRIFARI
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).
TRILLIANT
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 billiance.
TRILLION CUT
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 billiance.
TRIPLET
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).
TROY WEIGHT
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.
Troy
Unit |
Equivalence |
1
pennyweight |
24
grains = 1.5552
grams |
1
Troy ounce = 20
pennyweight |
31.1035
grams |
1
Troy pound = 12
Troy ounces |
373.24
grams |
TSAVORITE
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
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.
TUMBLER
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 other's surfaces.
TURQUOISE
Turquoise is 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
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).
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