tugumuda.com » Glossary

Jewelry Dictionary

tugumuda — Wed, 25 Jun 2008 05:04:44 +0000

A
abraded culet A chipped or scratched culet. Can be caused by contact with another diamond.
abrasion A bruise or scratch on the surface of a stone.
AGS American Gem Society. Professional organization formed in 1934 by several independent jewelers and the founder of the Gemological Institute of America (GIA). The AGS is dedicated to setting and maintaining ethical standards and practices within the industry.
Antwerp Perhaps the most noteworthy and versatile diamond-cutting center in the world. All sizes and shapes of rough diamonds are cut in Antwerp.
appraisal A monetary evaluation, usually performed for insurance purposes by a gemologist. Appraisals should describe the piece in detail, including color, clarity, proportions, stone sizes, flaws and other distinguishing characteristics.

B
baguette A rectangular cut stone with squared corners.
bearding Small feather-like cracks along the girdle of a diamond.
bezel Outer ring of a watch case, usually designed to hold the crystal, that may also be used for advanced functions like diving timers.
bezel setting Holds a gemstone in place on all sides at the girdle, creating a smooth, metal halo flush with the stone’s crown. Bezel settings often give the impression of a larger stone.
blemish A flaw, spot or scratch on the surface of a gemstone.
brilliance The intensity and amount of light reflecting from inside a diamond or gemstone.
brilliant cut The most common style of cutting for diamonds and colored stones. Brilliant cuts may be round or fancy and must have 57 or 58 facet cuts.
C
cabochon A gemstone cut that creates a dome shape with no facets.
caliper Instrument for determining the thickness or diameter of a gemstone.
carat One of the “Four Cs”. Metric unit of weight for diamonds and gemstones. One carat equals 200 milligrams or 0.2 grams.
clarity One of the “Four Cs”. Measures the degree to which a gemstone is free from flaws. A clarity scale is used to grade flaws in gemstones. The scale ranges from FL (Flawless) where there are no visible internal or external flaws to I3, where many imperfections are visible to the naked eye.
cleavage Tendency of a crystalline material to break in certain directions, often along a grain or crystal face.
cloud Group of tiny white inclusions in a diamond.
color One of the “Four Cs”. In diamonds, the color scale ranges from D (colorless) to Z (yellow). In colored gemstones, the grading scale differs widely depending on the type of stone.
comfort fit Ring design in which the edges of the shank are rounded for maximum comfort.
crown The facets or portions of a gemstone located above the girdle.
culet A small polished facet located at the sharp point or base of a faceted diamond or gemstone.
cultured pearl Pearls created by the artificial introduction of a mother-of-pearl irritant into an oyster or other mollusk. Cultured pearls generally have thinner nacre and lack the luster of a natural pearl.
cut One of the “Four Cs”. Perhaps the most important factor in determining the value of a diamond or gemstone. The cut refers to the geometric proportion that dictates the reflection and refraction of light within a stone.
D
depth The distance from a gemstone’s table to its culet (top to bottom).
depth percentage The measurement of a gemstone’s depth (top to bottom) in relation to its diameter. Depth percentage is primarily responsible for refraction, which produces the fire or sparkle in a gemstone.
Diamond Gauge A mechanical device used to determine the precise measurements of a gemstone.
DiamondLite Instrument for color grading diamonds using visual comparisons to master diamonds. Trademark, Gemological Institute of America.
dispersion The separation of white light into the full color spectrum. Often described as the “fire” or sparkle when discussing diamonds.
E
emerald cut Step cut gemstone (most often rectangular) whose corners have been cut off.
extinction Dark or black spots in colored stone.
eye-clean Gemstone in which the flaws cannot be seen without a 10x loupe.
F
facet Flat, polished surface or plane on a gemstone.
faceted girdle Girdle that has been cut with facets.
fancy shapes A gemstone shape other than round.
feather Internal flaw (inclusion) that has a feathery appearance.
findings Small, pre-fabricated parts of jewelry such as clasps, settings, etc.
fire The sparkles of flashes of spectral colors emitted from diamonds and other gemstones.
flaw General term used to refer to internal or external characteristics of a gemstone (i.e., inclusion, fracture, etc)
flawless Term used to describe a gemstone that lacks discernable internal or external blemishes when viewed by a gemologist using no less than 10x magnification.
fluorescence Luminescence that appears when certain diamonds are exposed to ultraviolet light.
fracture Cracks, feathers or chips in a gemstone.
full cut Gemstone with 58 facets.
G
gemologist Gemstone specialist trained in gem identification, grading and appraising.
gemology Science and study of gemstones.
GIA Gemological Institute of America. Non-profit organization specializing in grading diamonds and gemstones. Widely held as the premier laboratory for gemological grading.
girdle The narrow rim around a gemstone separating the crown from the pavilion.
gold filled Metal covered by a thin layer of gold that is at least 10k and 1/20th of the total weight of the piece
gold plated Virtually the same as gold filled, except gold plated items may have a layer of gold that is less than 1/20th of the total weight of the piece
grading Valuing a diamond using master stones.
H
head Portion of a jewelry item that holds the stone.
I
IJO
imperfection General term used to refer to internal or external characteristics of a gemstone (i.e., inclusion, fracture, etc)
inclusion Visible internal flaws in a gemstone, including fractures, crystalling abnormalities, and foreign objects.
irradiation Treatment performed on gemstones and even pearls to enhance color.
K
karat Standard measure of gold purity. One karat is 1/24th pure.
L
laser drilling Technique used to enhance a stone’s clarity by allowing for the introduction of bleaching agents or other enhancing agents.
leakage Light leaving, or escaping, through the facets of fashioned gemstone.
Leveridge gauge A millimeter gauge used to measure both mounted and unmounted stones.
loupe Small magnifying glass, often held in the eye socket, used for analyzing gemstones.
luster The appearance of a material’s surface, as determined by the quantity and quality of light reflected.
M
marquise Oval shaped gemstone with ends sharpened to points.
master stones A set of diamonds used to grade the color of other diamonds.
milgrain Tiny beads of metal used to decorate bands of metal
Moh’s Scale Scale used to measure gemstone hardness. Scale ranges from 1 to 10.
mounting Method of holding gemstones in place (i.e., prongs, bezels, etc)
N
nacre Crystalline substance that forms a pearl when secreted by a mollusk in response to an irritant.
O
off color A stone presenting any semblance of undesirable color.
oiling Temporary treatment used to enhance the color of a gemstone.
opera A strand of pearls 32 inches in length.
P
pave (pah-vay’) setting Style of setting small stones as close together as possible. Stones are set into drilled holes and metal beads are pushed over to hold the stone.
pavilion The portion of a gemstone located below the girdle.
percussion mark Indentation or bruise on the surface of a gemstone caused by contact from a pointed object.
pit Indentation on the surface of a diamond or gemstone.
platinum Precious metal that is far harder than gold. Platinum does not tarnish and is hypo-allergenic.
plot Diagram of a gemstone’s clarity characteristics. Generally performed during an appraisal using magnification.
point One-one hundredth (0.01) of a carat.
princess A strand of pearls 18 inches in length.
princess cut Square cut, brilliant gemstone.
prong Metal “finger” bent around the girdle of a gemstone to hold it securely in place.
proportion Mathematical representation of a gemstone’s overall symmetry.
R
recutting Refinishing a polished stone in order to improve the stone’s clarity, proportion or other imperfection.
reflection Light rebounding off the polished surfaces of a gemstone.
refraction Bending of light waves. When white light is refracted, a full spectrum of color appears, as in a prism.
rope A strand of pearls 40 inches in length.
rough An uncut or unpolished diamond or gemstone.
S
setting Method of holding gemstones in place (i.e., prongs, bezels, etc)
shank Part of the ring that encircles the finger.
single cut A simple form of cutting that has a table, approximately 16 facets and rarely a culet.
solitaire Ring containing a single diamond or gemstone.
symmetry Uniformity of a gemstone’s cut, including the shape and placement of facets.
synthetic stone “Man-made” gemstone grown in a lab.
T
table Largest facet on a gemstone. The table sits atop the crown and allows light to enter and exit, creating the stone’s brilliance.
table percentage Diameter of a gemstone divided by the size of the table.
Tolkowsky, Marcel Mathematician that defined the proportions necessary for maximum brilliance from a round diamond brilliant cut
U
ultrasonic Cleaning device for jewelry that removes dirt through the use of ultrasonic waves. Note: Certain gemstones may be damaged by an ultrasonic cleaner.

Glossary – OPAL

tugumuda — Sat, 31 May 2008 11:53:06 +0000

Andamooka:

A mining town in South Australia, situated 520km north of
Adelaide that produces precious opal and treating matrix opal. Opal was
discovered in Andamooka in 1930 in the form of floaters below what is now known
as Treloar Hill. The first opal miners of the area were Treloar and Evans, and
their first recorded production of precious opal was in 1933.

Andamooka Matrix: (Class C2)

A very white, porous opal found only in Andamooka which is
dyed black, giving the play of colors a black background in which to weave
their magic. This was done as early as the 1950’s by soaking the opal in a
sugar solution first, then sulfuric acid which burnt the sugar and turned it
black. Andamooka matrix is very rare and sought after today.

Arrow Head:

The pointed head or striking tip of an arrow.

Baguette Cut:

A rectangular step cut.

Bangle:

A piece a jewelry worn around the wrist.

Base/Body Color:

The background color of an opal, not taking into account the
play of colors on or near the surface.

Base Metal:

Any of certain common metals (as distinct from precious
metals) that are coated or plated with precious metals.

Belemnite: (Class A)

A conical fossil tapering to a point at one end with a
conical cavity at the other end containing (when unbroken) a small chambered
phragmocone from the shell of any of numerous extinct cephalopods of the family
Belemnitidae. Found in seas and oceans of the Mesozoic era, between 66-245
million years ago.

Belemnoid:

See Belemnite.

Belt Buckle:

A clasp used to fasten and adjust a belt.

Belly Stud:

A stud that is worn through the belly button.

Bezel Set:

This is a type of setting where the gemstone is set into a
piece of jewelry and completely surrounded by a metal perimeter. The outer rim
of the metal is burnished, or bent over and smoothed out around the girdle of
the gemstone. Bezel settings are extremely secure.

Black Crystal Opal:

A solid opal that is translucent to transparent with a play
of color, which when viewed from the top is graded as black opal.

Black Opal:

A solid opal that is opaque and has a play of color against
a black background when viewed from above.

View our stunning collection of Black Opal.

Body Art:

Jewelry associated with body piercing, e.g. nose ring, belly
stud etc.

Boulder Doublet: (Class B)

A two part assembled gem made of precious opal (transparent
to translucent) and an opaque ironstone backing glued to it (Queensland
boulder), giving the finished opal a black opal look. Doublets are an
inexpensive way to purchase high quality opal because only a thin piece of opal
is used.

Boulder Opal:

A seam or patches of precious opal still attached to the
host rock in which the opal formed. Highly valued and sought after for its
brilliant colors and patterns. Most boulder opal is mined in Queensland, Australia.

Bracelet:

A piece of jewelry worn around the wrist.

Brass:

An alloy of copper and zinc.

Brilliant Cut:

A type of cut which is generally composed of triangular and
kite shaped facets.

Broad Flash:

A pattern in which large sheets of color cover most (if not
all) of the opal’s surface.

Bronze:

An alloy of Copper and Tin and sometimes other elements.

Brooch:

A decorative pin worn by women.

Cabochon:

A solid opal (or other gemstone) cut into an elliptical,
round or polygonal shape with a flat base and a domed top. A stone cut in this
manner is described as being cut ‘en cabochon’.

Calibrated:

An opal that has been cut to a standard dimension (example
9mm x 7mm).

Carat:

A unit of measure used to express weight of gemstones
(1carat = 0.2 grams).

Carving:

See Opal Carving.

Choker:

A piece of jewelry that fits tightly around the neck.

Clarity:

The degree of transparency of an opal.

Claw Set:

This is a type of setting where the gemstone is set into a
piece of jewelry with fine wire claws (gold, silver etc). The claws are bent
over the stone and hold it in place. Claw settings are known to sometimes catch
on fabric but remain very popular because they showcase almost the whole
gemstone.

Color:

The color or combination of colors exhibited in precious
opal; does not take into account the color of the stone itself, but only the
play of colors within the stone. If one color is very predominant in an opal
then the color of that opal will be that color e.g. an opal that is
predominantly red with a little blue will be classed as red. If two colors are
predominant (e.g. red and gold), then it shall be classed as red/gold. The
minor colors will be listed in the description. If an opal has three dominant
colors then it is classed as a multicolor.

Color Bar:

A layer of color in opal.

Coober Pedy:

An opal-mining town in central South Australia. Coober Pedy
lies in the Stuart Range, 750km north of Adelaide. Since the discovery of
precious opal there in 1915, Coober Pedy has been the world’s largest producer
of precious opal.

The first white person to discover opal in the area was a 14
year old boy by the name of J.S. Hutchinson, looking for water to take back to
his father’s camp. His Father, along with a group of other men were prospecting
in the area for gold. Big Flat was the first established opal field in 1916.
The underground style of living gave Coober Pedy it’s name, which is derived
from the Aboriginal ‘kupa piti’ meaning ‘white mans burrow’. Today, opal
workings extend more than 40km north and 10km south of the township.

Copper:

A ductile malleable reddish-brown corrosion resistant
diamagnetic metallic element (Cu).

Crystal Opal:

Transparent to translucent solid opal with flashes of color;
highly valued due to the brilliance of its colors and the fact that many layers
of color can be seen within the stone.

Cufflinks:

A pair of linked buttons used in the cuffs of a shirt.

Cut Opal:

Opal that has been cut, sanded and polished and is ready to
be set into jewelry.

Dark Crystal:

Dark crystal opal is a transparent to translucent type of
opal whose base is not a clear crystal but a dark or smoky crystal.

View our entire collection of Dark Crystal Opal.

Diffraction:

A deviation in the direction of a wave of light.

Doublet: (Class B)

See Opal Doublet.

Drop Earring:

A style of earring that hangs below the ear.

Dot Painting:

The aborigines of Australia have a very unique and beautiful
method of creating stunning paintings by using many small dots to make the
drawing, usually telling a story from the past.

Earrings:

Any type of jewelry that is designed to be worn on ones
ears.

Emerald Cut:

The name used for a rectangular cut with truncated corners.
This style of cut was apparently developed especially for emeralds but is now
used to facet many different gemstones.

Fine Silver:

A soft white precious metallic element (Ag).

Fire:

Refers to the diffracted color play of an opal.

Flash:

A pattern in opal that is very bright.

Floaters:

Pieces of opal or nobbies eroded from their original host
rock and found in creeks, water courses and on low lying land below mesas (flat
top hills) or escarpments.

Fossil Opal:

Opal that has filled cavities in the ground left behind by
once living organisms e.g. opal belemnite, opal shell, opal shell-skin, opal
snail, opal specimen etc.

Free Shape:

An opal that has been cut according to the natural shape of
the stone.

Freeform:

An opal that has been cut into an irregular shape.

Full Color:

Opal that displays a play of color throughout the whole
stone from edge to edge.

Gem Quality:

This is the finest grade opal available.

Gold Plated:

Jewelry that consists of a base metal with a thin coating of
gold; usually produced by electroplating.

Gray Base:

A solid opal that is opaque with a gray base/body color.

Harlequin:

The rarest and most sought after pattern in opal. The colors
have formed naturally into a checkerboard pattern.

Hoop Earrings:

A circular band of precious metal with or without a gemstone
worn on the ears.

Inclusion:

Non-opal within precious opal. These can be grains of sand
or other natural materials. Inclusions can greatly affect the price of opal in
an upward and downward manner and sometimes not at all. If an inclusion is
deemed to detract from the stone, then the value is greatly reduced. If
however, an inclusion adds a new character or dimension to an opal, then it can
increase the value immensely.

Inlay Setting:

A solid opal fitted into a cavity and cemented into place.

Irregular Pattern:

A pattern within opal lacking uniformity or symmetry.

Jasper:

An opaque form of quartz.

Jelly Opal:

A transparent type of precious opal (similar in appearance
to crystal opal)which does not display a defined, regular pattern when idle,
but when rolled or moved has flashes of color.

Lambina:

An opal mining field situated around 200km north of Coober
Pedy. Lambina is a small camp on a large station in northern South Australia.
Conditions are very difficult due to it’s isolation and extreme weather
conditions, especially in the summer months when temperatures often exceed 45C.

Lightning Ridge:

A mining town in New South Wales famous for its black opals
(mostly nobbies and some seam). The first parcel of opal from Lightning Ridge
was mined and sold in 1903 by Charlie Nettleton. He had difficulty selling the
parcel because the opal was so dark. By 1908 black opal mined in Lightning
Ridge was fetching 50 times the price it did in 1903. Today, Lightning Ridge
produces the worlds most sought after and highly valued black opal.

Loose Opal:

Loose opal refers to cut and polished precious opals.

Marquise Cut:

The name given to a cut which is pointed at both ends, with
the sides being portions of a circle.

Matrix:

A host rock within which something originates (From the
Latin word womb). See also Andamooka Matrix.

Metal Type:

Describes the purity and type of metal used in a particular
piece of jewelry.

Milky Opal:

Opal with a white base/body color.

See White Opal.

Mintabie:

A mining town situated 350km northwest of Coober Pedy in
northern South Australia. The first white opal miners came to the area in the
early 1920’s but the local Aboriginals had sold black opal, which more than
likely came from from Mintabie, as early as 1915. Mintabie was the largest
opal-producing field in Australia from 1985 to 1989 in value, although the
greatest volume of precious opal still comes from Coober Pedy.

Mohs’ Scale:

The Mohs Scale of Hardness (1-10) came into accepted use
around 1812. It was conceived by the German mineralogist Frederick Mohs in
which 1 represents the hardness of talc and 10 represents the hardness of
diamond. The hardness of a mineral is a measure of it’s resistance to
scratching. Opal has a hardness in Mohs’ Scale of between 5.5 and 6.5. The
scale below includes ten common substances for comparison.

1: Talc__Can be scratched with a fingernail

2: Gypsum__Can be scratched with a fingernail

3: Calcite__Can be scratched with a penny

4: Fluorite__Easily scratched with a knife

5: Turquoise__Can be scratched with a knife

6: Opal__Can be scratched with a steel knife

7: Amethyst/Quartz__ Scratches window glass

8: Topaz__Scratches anything 8 or below

9: Ruby/Sapphire__Scratches anything 9 or below

10: Diamond__Scratches all

Mosaic:

Small pieces of opal fitted alongside each other.

Multicolor:

An opal which displays at least three distinct colors.

Natural Cut:

This type of cut is one where the opal has been left as true
to its natural shape as possible.

Necklace:

A cord or chain (often bearing gems) worn around the neck.

Necklet:

Something worn around the neck.

Night Stone:

An opal which is displays a very bright play of color in low
light.

Nobbies:

Pieces of opal derived from erosion of a vertical or level.
The term is rarely used in South Australia, but commonly used at Lightning
Ridge and refers to opal found in the form of small nodules.

Number of Pieces:

The total number of pieces in a particular parcel.

Number of Stones:

The total number of stones in a particular parcel.

Opal:

Geological Definition: Opal is a non crystalline form of the
mineral silica which, despite its amorphous structure, displays an amazing
degree of internal organization. Includes all hydrates of silica, SiO2 nH2O,
including synthetic, natural precious and common opal but not imitation material.
Alternative term is opaline silica.

Opal miners generally restrict the use of the term opal to
precious opal. Opal that does not exhibit a play of colors is referred to as
potch. See also Potch.

Opal Belemnite: (Class A)

Opal that has flowed into a cavity in the ground left behind
by a belemnite.

Opal Carving:

A piece of opal that has been carved into a particular
shape.

Opal Category:

This is the category the opal being viewed falls into, e.g.
black opal, crystal opal, black crystal opal, jelly opal, milky opal, dark
crystal, boulder doublet, matrix, boulder opal, (Gem, A , B and C grade for
triplets) etc.

Opal Chips: (Class A)

Small pieces of rough opal.

Opal Doublet: (Class B)

A two part assembled stone consisting of precious opal
cemented to another stone; this can be opal or another stone. See also Shell
Skin Doublet, Boulder Doublet.

Opal Potch:

See Potch.

Opal Shell: (Class A)

Opal that has filled the cavity left behind by a sea-shell.

Opal Shell Skin: (Class A)

Opal that has flowed into the cavity left behind by a
sea-shell which was open and thus the middle of the shell filled with soil and
only the cast left behind by the shell itself filled with opal.

Opal Size:

The outer dimensions (length x width) of a piece of opal
expressed in millimeters.

(25.4mm = 1Inch)

Opal Snail: (Class A)

Opal that has filled the cavity in the ground left behind by
a sea-snail.

Opal Specimen: (Class A)

A piece of opal that is more suited to be kept as a specimen
rather than be cut for jewelry.

Opal Triplet: (Class B)

A cut opal consisting of three layers; Clear quartz on top,
a thin slice of precious opal in the center and a black base all glued together
and shaped. Triplets are very good value for money because only a thin piece of
precious opal is used. All triplets are backed onto a black background thus
giving them the appearance of black opal.

Opaque:

Not see thru.

Origin:

The geographic location where a particular opal was mined.
All our opal has been mined in Australia. See also Andamooka, Coober Pedy,
Lambina, Lightning Ridge, Mintabie, Yowah.

Painted Lady:

A boulder consisting of precious opal laid in a sheet on one
side.

Pattern:

The pattern made by the play of color in an opal. Varieties
of pattern include, small, medium and large pattern; pinfire, rolling flash,
broad flash, harlequin

Pattern Type:

The type of pattern displayed in an opal. See also Pattern

Pear Shape:

A shape that starts off at a point and widens. Also called a
teardrop

Pendant:

An adornment that hangs from a necklace.

Pewter:

Various alloys of tin with small amounts of other metals
(especially lead).

#Pieces:

This is the amount of individual pieces making up the
parcel.

Pinfire:

A type of pattern which consists of small, pinpoint circles
of color.

Pipe: (Class A)

Miners term for Belemnite. See Belemnite.

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Platinum:

A heavy precious metallic element; gray-white and resistant
to corroding. Occurs in some nickel and copper ores and is also found native in
some deposits.

Plesiosaurus:

A now extinct sea reptile distinguished by a very long neck,
a small head, paddle-shaped limbs and a short body and tail. Growing to a total
length of about 12 meters when mature. Plesiosaurus roamed the inland seas of Australia and other places during the Jurassic and Cretaceous era.

Polished Opal:

Precious opal that has been cut into any shape, sanded and
polished and is ready to be set into jewelry.

Potch:

Can be black, white, crystal, honey or blue opal that
displays no play of color.

Potch and Color:

Opal that consists of mainly potch with only a small amount
of color in between.

Precious Opal:

Opal which displays a play of color in a distinct pattern.

Price:

The selling price of a product. This price does not include
shipping costs, or any taxes or duties (if any) that might be payable on
arrival to you. Shipping fees will be calculated for you in your cart according
to destination and chosen shipping method. Duties and taxes payable vary
between countries. If you are unsure if any duties or taxes will apply to you,
please check with your local customs office.

Price per gram:

This is the price per gram and not the total price of a
parcel. The total price is equal to the price per gram multiplied by the number
of grams.

Product Type:

This is the type of product within the category you are
viewing, e.g. solid opal, opal doublet, opal triplet, opal shell, opal
shell-skin, opal belemnite, opal ring, opal pendant, dot painting etc.

Rhodium:

A hard metallic element that is one of the platinum group
and is found in platinum ores; used in alloys with platinum (Rh).

Rhodium Plated:

Jewelry that consists of a base metal with a thin coating of
rhodium; usually produced by electroplating.

Ribbon Pattern:

A pattern in opal that resembles ribbons of color. Opals
displaying this characteristic are very rare and highly valued.

Ring Size:

By default, ring size for custom opal jewelry is shown as US
Ring Size. To convert your local ring size to US size, please click the
‘International Ring Sizes’ link on the page of the inlay opal ring you are viewing
and our ring size converter will pop-up. Just match your local ring size to the
US ring size from our chart.

Rolling Flash:

A color pattern in which sheets of color roll across the
surface of the opal as it’s moved or tilted.

Rough Opal: (Class A)

Precious opal in its natural state. May have been snipped
from the host rock and tumbled to minimize waste but has not been ground,
polished or shaped at all.

Rubbed Opal: (Class A)

A term usually referring to nobbies of Lightning Ridge opal
whose surface has been ground or sawn in order to expose the color of the
stone.

Sandstone:

A sedimentary rock consisting of sand consolidated with some
cement (clay or quartz).

Seam Opal:

Opal formed in a horizontal or near horizontal layer.

Setting Type:

Setting refers to the style by which a gemstone is held to
an item of jewelry e.g. bezel set, claw set, inlay setting etc.

Shape:

This term refers to the shape that an opal has been cut
into. Shapes can be oval, round, teardrop, freeform, free shape etc.

Shell: (Class A)

See Opal Shell.

Shell Skin: (Class A)

See Opal Shell Skin.

Shell Skin Doublets: (Class B)

A doublet in which the precious opal is opalised shell skin.
The backing can be potch or other materials.

Size:

The physical size of a product: 1 inch = 25.4mm / 1 inch =
2.54cm

Snail: (Class A)

Opalised mould left behind by a sea snail.

Solid Opal: (Class A)

A solid gem cut from natural precious opal with no other
type of stone present (cemented or otherwise).

Specimen:

See Opal Specimen.

Stainless Steel:

Steel containing chromium that makes it resistant to
corrosion.

Sterling Silver:

A silver alloy with no more than 7.5% copper.

#Stones

The total number of opals in the parcel.

Straw Pattern:

Stud Earring:

A type of earring that that does not hang down below the
ear. It has an outer face and a pin attached to the rear that goes through the
ear.

Style of Cut:

Describes the top surface shape of an opal, e.g. flat,
cabochon, uneven, undulating, natural cut etc.

Teardrop:

A term used to describe an opal or other precious gemstone
that has been cut into a pear-shape.

Thickness:

The outer thickness of a stone measured from the back to the
front (face) of the stone.

Tie Pin:

A pin used to hold a tie in place.

Time:

This is the approximate amount of time needed to custom make
your order (not including delivery time). Times will generally be less than
stated but not longer.

Titanium:

A light, strong, lustrous corrosion resistant metallic
element (Ti).

Toe Ring:

A ring that is worn on the toes.

Total Price:

The total sale price of a product (excluding postage and
handling).

Translucent:

Semi-Transparent.

Transparency:

The ease with which one can see through an opal. See also
Transparent, Translucent and Opaque

Transparent:

See thru.

Triplet: (Class B)

See Opal Triplet.

Type of Opal:

See Fossil Opal.

Undulating:

Rising and falling.

Uneven:

Not level.

Vertical Opal:

Opal formed in a vertical or near vertical layer.

Weight:

The total weight of a product. For all cut opal and fossil
opal weight is expressed in carats (5carats = 1gram), and for rough opal and
opal jewelry it is expressed in grams.

White Cliffs:

A mining town in New South Wales.

White Opal:

Common form of gem quality opal which is opaque and
possesses a white body color. White opal is often referred to as milky opal.

Yowah:

A mining town in Queensland.

Yowah Nut:

An unusual boulder matrix found only in Yowah.

Zinc:

A bluish-white lustrous metallic element (Zn).

source

.

Diamond Glossary

tugumuda — Sat, 31 May 2008 01:45:06 +0000

Diamond Glossary
Read it for the answer

Brilliance:	White light captured from all the surfaces of the diamond and reflected up through the top. A diamond with the correct proportions yields the highest brilliance.
Brilliant Cut:	A brilliant cut has triangular facets that surround the stone that culminate on a flat top. A brilliant cut can be round, marquise, oval, pear-shaped, heart-shaped, princess (square), or radiant.
Carat Weight:	A unit of weight for diamond equivalent to 200 milligrams.
Carbons:	A flaw on the surface of a diamond that looks like a very small black dot.
Clarity:	Describes the number and extent of flaws that a diamond may have. Clarity is graded on a scale that ranges from Flawless (FL) to Imperfect (I3).
Cloud:	Hazy areas within the diamond, actually made up of many small crystals that are impossible to see individually.
Color:	Describes the “yellowness” of a stone. The color scale ranges from D (colorless) to Z (deep yellow)
Crown:	The top portion of a diamond, from the girdle (the thickest part around the stone) to the table (the top surface facing the viewer).
Crystal Growth:	A small crystalline growth within the diamond. Looks like a small diamond within the big diamond.
Culet:	The bottom “tip” of the diamond, where the facets of the pavilion converge.
Cut:	Perhaps one of the most misused of the 4 C’s, it refers to the style of cut (brilliant, emerald), the shape of the stone (round, heart-shaped), and the geometric proportions to which the diamond is cut.
Cut Style:	Refers to whether a stone is a “brilliant cut” or an “emerald cut,” or a hybrid of the two.
Depth:	The height of a diamond, measured from the culet to the table.
Depth Percentage (%):	The height of a diamond divided by the width of the diamond. The depth percentage is one of the many metrics used to measure how well proportioned a diamond is cut, and consequently how much “sparkle” it will have.
Emerald Cut:	An emerald cut is more “glassy” in appearance, since its facets usually span the length or width of the stone. Emerald cuts are different from step cuts in that their corners are rounded.
Facet:	The flat polished surfaces on a diamond. Brilliant cuts have 58 triangular facets and therefore “sparkle” more than emerald cuts, which have far fewer facets and therefore have a more “glassy, elegant” look.
Feathers:	Small cracks within the stone, similar in look to broken glass. Small internal feathers are harmless (other than lowering the clarity rating of the diamond), but large feathers can become a problem because the crack can grow as the diamond ages.
Fire:	When light is refracted within the diamond, the result is that multi-colored light beams out of the table, and it somewhat looks like fire. For maximum fire, seek out a well-proportioned stone.
Flaw:	A scratch or abrasion on the surface of a diamond, or a defect within the crystalline surface of the diamond. The most common flaws are: Pinpoints, Carbons, Feathers, Clouds, and Crystal Growths.
Fluorescence:	A bluish glow within the diamond when exposed to ultraviolet light. Some people like fluorescence and some don’t. In any case, strong fluorescence should be avoided.
Girdle:	The narrow band around the width of the diamond, where the crown and pavilion meet.
Inclusion:	See Flaws
Pavilion:	The bottom portion of a diamond, from the girdle (the thickest part around the stone) to the culet (the tip at the bottom).
Pinpoint:	A very small white dot on the surface of the stone. By far, the most common flaw that can be found on a diamond.
Point:	A weight measure equal to 1/100th of a carat. So for example, a 3/4 carat diamond is a “75 point diamond.”
Polish:	The final smoothness of the surfaces of a diamond. An excellent polish will result in a lower-weight stone, so most diamond cutters will make tradeoffs.
Proportions:	The proportion of a stone will directly influence how much “brilliance” and “fire” it has. See “depth percentage” and refer to the tutorial for guidelines.
Shape:	Refers to the way that the stone is cut. Common shapes are: Round, marquise, oval, pear-shaped, heart-shaped, princess (square), and radiant (also square).
Sparkle:	The combination of brilliance and fire that emanates from the diamond.
Step Cut:	An step cut diamond is “glassy” in appearance, since its facets usually span the length or width of the stone.
Table:	The largest surface on a diamond, located on the top of the diamond facing the viewer. The table culminates the crown of the diamond.
Table Percentage (%):	The width of the table divided by the diameter of the diamond. The table percentage is one of the many metrics used to measure how well proportioned a diamond is cut, and consequently how much “sparkle” it will have.
Workmanship:	Refers to the overall finish of the diamond, including the polish on the facets, the symmetry of facets with respect to each other, and the shape of the culet.