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A comprehensive glossary with the entire lingo you need to
know in order to better understand diamonds.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Abrasion
Small nicks on the surface of diamonds visible along facet
junctions. Gives the diamond a fuzzy look instead of sharp facet lines.
Adamas
Greek word which means unconquerable. The term diamond is
derived from this.
ADL
Renowned group that offers many services, pricelist and
support on the Antwerp
diamond market.
American Gem Society (AGS)
Professional jeweler's society with a renowned laboratory
that grades diamonds and provides diamond grading reports.
American Standard cut
Ideal cut
Antwerp
Diamond Bourse
Global market and meeting place for various diamond dealers
to trade in polished diamonds.
Appraisal
Written estimate specifying the approximate retail
replacement value of the diamond. The document can be used for insurance
purposes and needs regular updation.
Argyle
Diamond mining region located in Western Australia
Asscher
Fancy diamond present in the shape of a square emerald cut.
Originally designed by Asscher, an Amsterdam
based diamond cutter in 1900.
Asscher Cut Loose Diamond
Asterism
Star effect caused by light reflecting off inclusions inside
a diamond
Aventurescence
Shiny reflection caused when tiny inclusions sparkle in
light in a diamond.
Baguette
French term meaning rod or loaf of bread. Step cut of the
diamond giving it a rectangular shape.
Ballerina
Form of diamond setting where a large central diamond is
surrounded by a series of diamonds cut in baguette style. Setting looks like a
ballerina's skirt.
Bar setting
Diamond setting, where in a circular band of diamonds, each
stone is held by a long thin bar shared between two diamonds.
Bearding
Or bearded girdle refers to hair like fractures reaching
inside the stone
Bezel facets
Kite shaped facets also known as top main facets present on
the crown of a diamond.
Blemish
Imperfections present on surface of diamond.
Blood diamonds
Or conflict diamonds. Used to fund illegal activities of
terrorist groups..
Blue white diamonds
Initially referred to diamonds without a distinctive body
color. However now, as per Federal Trade Commission, refers to diamonds with
distinct blue body color.
Bort
Industrial grade of diamonds
Bow tie
Effect caused in fancy shaped diamonds when light leaks out
from the bottom of a diamond causing a shadowy area.
Bow Tie Affect
Brilliance
Reflection of white light coming from the diamond.
Brilliant cut
Round diamond with 57 facets (58 in case culet is present).
The most brilliant form of diamond as compared to other cuts.
Brillianteering
The last part of polishing diamond, where the brillianteer
adds twenty-four facets to the crown and sixteen facets to the pavilion.
Bruise
Surface inclusion with crumbling on the diamond's surface
along with tiny feathers.
Bruting
Cutting or girdling. Process involves grinding one diamond
against another to give it its basic shape.
Carat weight
Standard unit of weight of diamonds. One carat is equivalent
to 1/5 of one gram. Not to be confused with Karat, which is used for stating
the amount of pure gold.
Cavity
diamond flaw represented by a large hole in a diamond.
Canary diamonds
Diamonds that are golden yellow in color with fluorescence
in yellow, golden and orange colors. Also known as fancy yellow.
Canary Diamond
Centenary diamond
Weighing 273.8 carats, this is the third largest diamond to
be produced from the Premier mine.
Central Selling Organization (CSO)
London
based trading arm of De Beers Consolidated Mines Ltd, commonly referred to as
the ‘Syndicate'.
Certificate
Laminated document provided by gemological laboratories to
verify the 4Cs of a diamond and its various characteristics.
Channel setting
Popular ring setting for wedding and engagement rings. Here
stones are set next to each other without any metal separating them.
Chip
Small missing piece in a diamond caused due to normal wear
and tear or due to diamond cutting.
CIBJO
World jewelry confederation that deals with diamonds, silver
and various other stones. Known as Confederation International de la
Bijouterie, Joaillerie Orfèvrerie des Diamantes.
Clarity
One of the 4Cs of diamonds to indicate the level of
flawlessness in a diamond. Graded on a scale from flawless (FL) to Imperfect
(I).
Clarity enhancement
Range of processes used to improve the clarity grade of
diamonds.
Cleavage
A break in diamonds parallel to one of its crystallographic
planes.
Cloud
A gathering of tiny inclusions in a diamond giving the stone
a cloudy appearance.
Cluster setting
Diamond setting, where one large central diamond is
surrounded by many small stones.
Coating
Coloring of a diamond with surface coating to hide
its true body color. The coating may be extensive or limited to a couple of
pavilion facets.
Colored stones
All natural gemstones, except diamonds.
Crown
Portion of the diamond above the girdle to the table.
Crown angle
Angle formed between the girdle plane and bezel facets. It
helps to determine the amount of light dispersion and hence the brilliance of a
diamond.
Crystals
Diamond inclusions in the form of mineral deposits or other
diamonds inside the diamond.
Crystallography
The internal structure of a diamond (usually as octahedron,
tetrahedron, cube or rhombic dodecahedron) that has a direct influence on its
external morphology.
Culet
Smallest facet that may be present at the bottom of a full
cut diamond. Is of negligible diameter or will cause light to leak out from the
diamond.
Cullinan diamond
One of the largest ever diamonds (original weight of 3106
carats) to be discovered in the Premier mines of South Africa.
Cushion cut
A mixed cut in diamond giving it the shape of a square
pillow.
Cut
One of the 4Cs of a diamond that determines its brilliance
and overall beauty. It refers to the proportions given by a diamond cutter.
Dahlia
A form of diamond shape where the stone is oval in shape
with flat ends. The stone has 51 facets, with 37 on the crown and 14 on the
pavilion.
Diamond
A crystal of over 99% pure carbon, arranged in an isometric,
cubic or crystal form. Has a hardness of ten, refractive index of 2.417 and
3.52 specific gravity.
Diamond Development Initiative (DDI)
An initiative taken on with the mission to address the
political, social and economic aspects of diamond mining.
Dark field condition
Condition caused when a stone is tilted in an angle that
makes selected facets appear black. Prevalently used to locate flaws.
Depth percentage
Ratio which refers how deep the diamond is as compared to
its width. An important factor for measuring diamond brilliance and value.
Diamond gauge
Instrument used for measuring the length, width and depth of
diamonds in millimeters.
Diamond radiation
Diamond enhancement method of irradiating diamonds with high
energy particles like protons or electrons to displace the carbon and cause
color centers.
Dispersion
Rainbow of colors obtained when white light passes through a
diamond.
Doublets
Diamond imitations or simulants that are made of two or more
components. Usually comprise of a synthetic stone with a thin layer of natural
diamond.
Dubai Diamond Exchange (DDE)
Organization in Dubai that
facilitates the trade of both rough and polished diamonds in Dubai.
Emerald cut
Rectangular shape of a diamond giving it cut corners. Also
known as step cut.
Epigenetic inclusions
Inclusions formed in a diamond after its formation. Usually
caused during mining and processing.
Eppler system
European system followed for measuring proportions of ideal
diamonds, popular in Germany.
European Gemological Laboratory (EGL)
Renowned gemological laboratory that grades diamonds and
gives certification regarding diamond characteristics.
Excellent cut
Grade awarded by GIA and HRD for brilliant diamonds that
have an excellent polish and cut.
Extra facet
A false facet that is placed in a diamond without any actual
use for it or without any regard to symmetry.
Eye clean
Diamonds that are graded with no inclusions visible through
the table with the naked eye
Face up
View of the diamond when it is seen from the top.
Facet
Polished planes present on the surface of a diamond
Faceted girdle
Result obtained from polishing the girdle for increased
reflection, such that a round diamond has 32 facets.
Fancy shape
Shape of a diamond other than round. Comprises of heart,
marquise, pear, oval, emerald and trillion shapes.
Feather
Fracture in a diamond resembling the form of a feather
Fingerprint
Rare form of diamond inclusion found on diamond surface in
the form of fingerprints.
Finish
The set of qualities attributed to a diamond after it is cut
and polished by a diamond cutter.
Fish eye diamond
Diamond with an extremely shallow pavilion less than 37% of
average diameter, making the stone look lifeless.
Flat top setting
Kind of diamond ring setting with a continuous band
Flaw
A defect present in a diamond
Fluorescence
Glow with visible light caused when high energy rays pass
through a substance. Visible in all rainbow colors with a domination of blue,
white, green, pink and yellow in diamonds.
Four Cs
The four major characterstics of cut, color, clarity and
carat weight that determine a diamond's quality
Fracture
Breakage in a diamond that is not parallel to the cleavage
plane
Fracture filling
Predominant yet temporary practice of sealing fractures on a
diamond
Full cut
Diamonds with a brilliant cut.
Gem quality
Stones selected during sorting process. Includes stones with
excellent colors, minimal flaws, crystal shapes and good sizes.
Gemological Institute of America
GIA
One of the world's leading gemological laboratory that does
extensive research on diamonds, grades them and provides grading certificates
GIA proportionoscope
An optical comparator used by GIA for checking proportions of
brilliant cut diamonds from .18 carats to 8 carats.
Girdle
Narrow band present around the outer circumference of a
diamond. The girdle can be rough or polished and represents the junction where
a setting holds the diamond.
Golden Jubilee
A yellowish brown renowned fancy diamond with the original
weight of 545.67 carats discovered in the Premier mines of South Africa.
Grain lines
Crystal
inclusions formed due to improper crystallization of diamond.
Heart shape cut
A fancy cut in diamonds, where the cut resembles the shape
of a heart.
High pressure High temperature (HPHT)
Form of diamond enhancement technique where high pressure
and high temperature are recreated (as in a diamond's natural environment of
formation) in order to improve diamond color.
Hope diamond
A renowned blue color fancy diamond weighing 45 carats,
known for bringing misfortune to its owners.
HRD
Hoge Raad voor Diamant. An independent and not for profit diamond institute and
laboratory of Antwerp
that provides impartial diamond certificates.
Ideal cut
Highest quality of cut, applicable only to round diamonds.
Gives the diamond high brilliance and high prices.
Inclusion
Naturally occurring diamond imperfections in the form of
pinpoints, crystals, needles etc.
Included
Clarity grades of I1, I2 and I3 awarded to diamonds with
medium and large inclusions visible to the naked eye.
International Diamond Council (IDC)
Formulated by the WFDB, IDMA and CIBJO in 1979 to create
universal rules for diamond trade.
International Gemological Institute (IGI)
An internationally acclaimed diamond laboratory that
provides grading reports and issues appraisals for diamonds.
Iridescence
The spectrum of colors present on the surface of a gemstone
or inside it.
Kimberlite
A rare form of igneous rock that may host diamonds in
primary deposits. Have high contents of volatile elements.
Knife edge girdle
An extremely thin girdle that can fracture when set.
Knot
Diamond inclusion present in the form of a crystal reaching
the diamond's surface.
Kohinoor
The renowned Indian diamond, rumored for its powers to make
the owner a ruler of the world. Weighs 108 carats approximately and is found in
the Tower of London.
Lamproite
Highly rare form of igneous rock that may host diamonds in
primary deposits.
Laser drilling
Diamond enhancement process that involves drilling a hole
into diamonds with the aid of laser beam to remove inclusions.
Laser identification
Process of inscribing diamonds with either a special
personal message or general information (regarding the diamond brand name,
number etc)
Length to width ratio
Ratio used to measure how long a diamond is as compared to
its width. Specially used for analyzing the outlines of fancy shaped diamonds.
Leveridge
A micrometer specially designed for measuring the
proportions of diamonds, especially expensive stones.
Loupe
Small magnifying lens used by jewelers to examine diamonds.
Usually comes with standard10X magnification, to prevent different evaluations
of the same flaw.
Loupe clean
Highest degree of clarity awarded by the International
Diamond Council whereby the stone does not have a pinpoint flaw larger than 5
microns in diameter when seen under a magnification of 10X.
Luminescence
The phenomenon that occurs when diamonds are exposed to UV light
causing them to fluoresce with visible light.
Luster
The quality and amount of light that reflects from a
diamond. An important attribute while purchasing diamonds, classified as high,
medium and low.
Make
The quality of finish and proportions in a diamond. A good
make enhances the brilliance of a diamond.
Makeables
Diamonds that go into polishing without going through the
initial preparatory stages of cleaving and sawing. Usually includes macles and
cleavages among other stones.
Marquise cut
Fancy shape in diamonds comprising of elongated points at
each end.
Master set
Set of diamonds (usually ones certified by GIA) used as a
standard to grade color in other diamonds.
Melee
Minute diamonds of size under 0.20 carats.
Mine cut diamond
An early form of brilliant diamond cut with square girdle,
large culet and high crown.
Mohs scale
The scale used for grading mineral hardness. Diamonds are
graded on 10, the highest figure of the Mohs scale. Devised by Friedrich Mohs,
a German minerologist.
Mounting
Trade term for the portion of jewelry on which a diamond is
set.
Naats
Another diamond inclusion which represents the junction at
which one diamond crystal is seen to be embedded inside a second diamond
crystal.
Natural
A form of diamond blemish where some diamond rough is left
on the polished surface of a diamond. Is usually done to maximize the weight of
a diamond.
Needle
A diamond inclusion whereby a thin needle like crystal is
present inside the diamond.
Nick
A small chip on the surface of a diamond, usually near the
girdle or the facet edge.
Off make
A diamond that is poorly proportioned
Old European cut
An early version of the round brilliant cut. The cut is
different from the modern round brilliant as it has a small table and large crown.
Open pit mining
Process of diamond mining that uses kimberlite pipes to
extract diamonds.
Oval cut
Another fancy cut in diamonds where the cut becomes an
elongated version of the round cut.
Pave
Jewelry setting where many small diamonds are mounted close
together to create a diamond crust which obscures the surface of the metal on
which the diamonds are mounted.
Pavilion
Portion of the diamond below the girdle
Pear cut
Another fancy cut in diamond resembling a tear drop.
Percussion mark
A dent or hole caused by external force, but leading to an
internal mark. This is considered as an internal flaw.
Phosphorescence
Also known as after glow. This phenomenon is called when
diamonds luminescent under UV light continue to fluoresce even when the light
is turned off.
Pinpoints
Small dot shaped inclusions in diamonds. Many pinpoints
together form a cloud inclusion.
Pit
Tiny opening on the diamond present as a surface blemish and
looking like a white spot.
Points
One by hundredth of a carat. It is used to measure diamonds
weighing less than a carat.
Polish
The finishing of a diamond's facets by a diamond cutter.
Polish is graded on the scale from poor to excellent.
Polish lines
White lines that appear on a diamond due to polishing.
Caused usually because of uneven surface of a diamond.
Polish mark
Marks in the form of white cloudy areas left on the diamond
due to application of high degree of heat or because of an uneven diamond
surface.
Princess cut
A fancy cut diamond that is either square or rectangular in
shape.
Protogenetic inclusions
Inclusions that predate a diamond and are noted to be
present in the vicinity of the stone while it was being created.
Radiant cut
Another fancy cut where the diamond is square or
rectangular, but has the corners cut off.
Repeated twinning
Also known as polysynthetic twinning. Refers to the manner
in which diamond crystallize as thin layers on top of each other.
Round brilliant
Refer to ideal cut
Saturation
The degree or presence of color in a diamond from the
neutral to vivid scale.
Sawing
The process undertaken to increase the options present for
preparing a stone. Can be undertaken mechanically or by using lasers.
Scaife
A horizontal wheel for polishing diamonds. The instrument is
powered by an electric motor that has speeds up to 3000 revolutions per minute.
Scan DN
Known as the Scandinavian system, a popular European
system of measuring the ideal
proportions of a diamond.
Scratch
A diamond flaw caused by rubbing diamond with abrasive.
Present in the form of tiny white lines.
Semi mount
A kind of jewelry setting where side stones are already
mounted, but an empty set of prongs is provided usually in the center to mount
a diamond.
Simulant
Imitation diamonds that are made of diamond like material,
either natural or synthetic. Marketed to look like real diamonds. Examples
include CZ, GGG, moissanite etc.
Single cut
Small round diamonds with approximately 16 facets instead of
the regular 57 facets. The cut is employed usually in pave settings or in cases
when many small diamonds are set together.
Solitaire
Term referring to a single diamond being set in a piece of
jewelry.
Sparkle
The amount of light reflected from a diamond as it moves.
Spread stone
A diamond that comes with a large table and thin crown
height.
Star facet
Facet found on the upper crown section of brilliant cut
diamonds next to the table. One of the eight triangular facets.
Symmetry
Graded by laboratories for diamonds on the basis of how
proportionate the diamond is and how the various facets are placed in
accordance with each other.
Syngenetic inclusions
These are the inclusions which were noted to be formed along
with the formation of the diamond. Noted to have originated from the same
geological layer and have developed along with the diamond.
Synthetic diamonds
Diamonds that are not naturally formed and are created by
humans.
Table
Largest facet present on the top of a diamond. The area from
where maximum amount of light enters and exits a diamond.
Table percentage
Figure derived from dividing the width of the table by the
average diameter.
Tang
An instrument used for manual polishing of diamonds.
Comprises of three parts known as the dop, stem and legs.
Tolkowsky cut
Form of round brilliant cut which is the benchmark for ideal
cuts in North America. Cut was discovered in
1919 by Marcel Tolkowsky, a renowned Belgian diamond cutter.
Tone
The position of diamond color on a grade from colorless to
black.
Topaz
A popular diamond imitation, which can easily be detected through
polariscopes.
Trilliant cut
A brilliant fancy triangular shape of diamond.
Twinning wisp
Cloudy area produced by distorted crystal inclusions that
intertwine.
Type I diamonds
Nitrogen containing diamonds that absorb ultraviolet rays
from 300nm. They also show distinct absorption bands in infrared regions of
780nm. Eg. Cape and brown series of diamonds.
These are further classified as Type
Ia (those containing highly
concentrated nitrogen as platelets) and Type Ib (where nitrogen is evenly
distributed throughout the stone).
Type II diamonds
Nitrogen free diamonds that do not show any absorption bands
in infrared regions and appear more transparent in ultraviolet light up to
220nm. Further classified as Type IIa (brown to light brown stones) and Type
IIb (natural blue stones).
Type III diamonds
Diamonds having a crystallographic structure that is
hexagonal instead of a regular cube. Usually discovered in meteorites and
synthetic diamond preparations.
Ultrasonic cleaner
A device used for cleaning diamonds and other gemstones
using ultrasonic vibrations. May come with a heater.
Upper girdle facet
One facet among the fifteen present on the lower crown of
the diamond.
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