|
Diamond Glossary
|
| 1. |
Abrasion |
Tiny nicks along facet junctions, producing white fuzzy lines instead of sharp crisp facet edges. Very often seen on synthetic gems and gems with a lower hardness factor. |
| 2.
|
Bearding
|
Tiny, numerous, hair like fractures extending into the diamond from the girdle.
|
| 3.
|
Bezel Facet
|
A facet on the crown, or upper part of the diamond above the girdle, there are 8 of them, kite shaped, also known as the main crown facets.
|
| 4.
|
Blemish
|
Surface imperfection shown in green when plotted.
|
| 5.
|
Brilliance
|
The amount of white light reflected back to the eye from a diamond.
|
| 6.
|
Brilliant
|
The most common cut, containing 57 or 58 facets if it has a faceted culet. The round brilliant cut diamond is the only shape that is cut with exact degrees and angles for maximum brilliance.
|
| 7.
|
Bow Tie
|
An effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the diamond.
|
| 8.
|
Bruising
|
An inclusion consisting of surface crumbling, often accompanied by tiny, root like feathers.
|
| 9.
|
Carat
|
The metric 'carat', 1/5 of a gram, 100 pts equal 1ct and is the standard unit of weight for diamonds and most other gems. If other factors are equal, the more carats, the more valuable it will be per carat.
|
| 10.
|
Cavity
|
An inclusion consisting of a large or deep opening in the diamond.
|
| 11.
|
Chip
|
A tiny piece missing from a surface edge of a diamond. Also used as a term for a small single cut diamonds.
|
| 12.
|
Clarity
|
A diamond's relative position on a scale that ranges from Flawless to Imperfect. 'Clarity' characteristics are classified as inclusions (internal) or blemishes (external). The size, number, nature, location and color of inclusion or the lack of characteristics determine the clarity grade. Very few diamonds are flawless, that means, show no inclusions or blemishes when examined by a skilled grader using 10X magnification.
|
| 13.
|
Cleavage
|
A separation along a plane of weak atomic bonding.
|
| 14.
|
Cloud
|
A group of minute white inclusions which result in a milky or cloudy like appearance.
|
| 15.
|
Coated
|
A diamond can be 'coated', i.e. colored by a surface coating which masks the true body color; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.
|
| 16.
|
Color
|
Grading 'color' in the normal color scale range involves deciding how closely a diamond's body color approaches colorlessness or white. Most diamonds have at least a trace of yellow -off white - body color. With the exception of some natural fancy colors, such as green, canary, blue, pink, purple, or red, the colorless white grade D+ is the most valuable.
|
| 17.
|
Crown
|
The upper portion of a gemstone above the girdle.
|
| 18.
|
Crown Angle
|
The angle measured between the crown facets and the table.
|
| 19.
|
Culet
|
The smallest facet at the bottom of the diamond.
|
| 20.
|
Cut
|
The proportions and finish of a polished diamond (also called make). 'Cut' can also mean shape, as in emerald cut or marquise cut. Proportions are the size and angle relationships between the facets and different parts of the diamond. Finish includes polish and details of facet shape and alignment. 'Cut' affects both the weight yield from rough and the optical efficiency or brilliance of the polished diamond; the more successful the cutter is in balancing these considerations, the more valuable the diamond will be.
|
| 21.
|
Cubic Zirconia
|
Also known as a CZ, a widely used imitation for a natural diamond. The CZ has a higher dispersion factor making them “too good to be true” and is 1.6 times heavier than a diamond.
|
| 22.
|
Diamond
|
The diamond is a rare crystal of native carbon [C atomic number 6 - an abundant nonmetallic tetravalent element] in isometric crystals, often (hex) octahedrons with rounded edges. The diamond is usually almost colorless, but some diamonds are yellow, green, blue, and even black. These colors are caused by impurities by other minerals, nitrogen ... yellow, boron ... blue, crystal irregularities ... pinks, browns and reds. It is the hardest (Mohs scale 10) mineral known. The diamond as found in nature (called a rough diamond) is cut and polished for use in jewelry into various forms with many reflecting faces, or facets, by which its brilliancy is much increased. The 58 facet round cut diamond is called brilliant; it is the most reflective and is used most often in the manufacturing of jewelry.
|
| 23.
|
Dispersion
|
The ability of a transparent gemstone to separate white light into the spectral colors.
|
| 24.
|
Extra Facet
|
A Facet in excess of those needed to achieve the planned symmetry of any given shape of diamond.
|
| 25.
|
Facet
|
A plane, polished surface of a diamond.
|
| 26.
|
Faceted Girdle
|
Small plane, polished surfaces on the girdle.
|
| 27.
|
Fancy
|
A diamond with a shape other than round cut (i.e. princess, emerald, oval, etc.) and/or with an attractive natural body color other than light yellow or light brown.
|
| 28.
|
Feather
|
A separation or break due to either cleavage or fracture, often white and feathery in appearance when viewed at right angles to the separation plane.
|
| 29.
|
Fire
|
Flashes of the spectral colors as a result of dispersion.
|
| 30.
|
Flaw
|
An imperfection of a diamond. A term used to refer to any internal (inclusion) or external (blemish) on a fashioned diamond.
|
| 31.
|
Fluorescence
|
The ability to change one kind of radiation to another. The visible wavelengths emitted by a diamond when exposed to invisible radiation such as x-rays or ultraviolet rays. Diamonds usually fluoresce blue but may glow light red, green, orange, or yellow. Ratings: none, faint, slight, medium, strong blue. Strong blue fluorescence may cause the diamond to appear milky in daylight.
|
| 32.
|
Fracture
|
A breaking or chipping of the stone along a plane other than the cleavage plane.
|
| 33.
|
Fracture Filled
|
A fracture can be treated by filling which can only be detected under special lighting with a high magnification microscope. This is a temporary treatment and great care needs to be taken when working with fracture filled diamonds.
|
| 34.
|
Full Cut Brilliant
|
A term used to for brilliant cut diamonds or colored stones with the usual 58 facets; 32 facets and the table above the girdle and 24 facets and a culet below the girdle.
|
| 35.
|
Girdle
|
The outer edge or the widest part of the diamond forming a band around the diamond separating the crown from the pavilion. Some cutters also polish the girdle into facets for maximal reflection.
|
| 36.
|
Girdle Thickness
|
The width of the outside edge of a polished diamond measured across the midpoints of the upper girdle and lower girdle facets. The results are a percentage of the diameter of the stone.
|
| 37.
|
Grain
|
¼ of a metric carat. Also used to refer to the cleavage direction.
|
| 38.
|
Green
|
Green diamonds: a rare natural fancy from lime to intense green color; many natural lighter green diamonds are mined in Sierra Leone. Others diamonds have been color enhanced to turn green by emanations from radium, a cyclotron, radiation or heat treated and this should always be disclosed to the consumer.
|
| 39.
|
Hardness
|
Mineral's resistance to scratching on a smooth surface. Mohs scale of relative hardness consists of 10 minerals (talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond), each scratching all those below it in scale and being scratched by all those above it. Diamond is at the top (10 on Mohs) and can be 10 to 150 times harder than a 9 because the diamond does not have the same hardness in all crystal directions.
|
| 40.
|
Hearts & Arrows
|
The hearts and arrows cut creates a perfectly symmetrical round brilliant diamond with 58 painstakingly cut and aligned facets which endlessly magnify light within the diamond. Under special illumination the diamond presents a perfectly symmetrical pattern resembling hearts and a star of arrows of the same length and width. The majority of Hearts and Arrows diamonds are manufactured in Antwerp as only few master cutters are able to create them.
|
| 41.
|
Ideal Cut
|
The specific angles and degrees calculated mathematically to produce maximum brilliance and fire in a round diamond. The percentages are all in relation to the diameter of the girdle.
|
| 42.
|
Included Crystal
|
A mineral crystal contained in a diamond that occurred during the growth process.
|
| 43.
|
Inclusion
|
A naturally occurring imperfection internal to the diamond, the unique 'birth mark' of a diamond. Inclusions are to be viewed with a 10x loupe.
|
| 44.
|
Internal Graining
|
Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.
|
| 45.
|
Karat
|
Karat (often confused with Carat -Ct- for gems) is used to state the purity of the precious metal in parts per 1000; example: 24K is 999.9, 18K is 750, 14K contains 585 pure gold.
|
| 46.
|
Knot
|
An included diamond crystal which reaches the surface of a polished diamond.
|
| 47.
|
Laser Drill Hole
|
A tiny tube made by a laser to enhance the appearance of an inclusion. The surface opening may resemble a pit, while the tube usually looks needle like.
|
| 48.
|
Laser Inscription
|
Miniscule superficial inscription created by a laser on the girdle of a diamond for identification.
|
| 49.
|
Loupe
|
Precision magnifying glass, usually of 10X and set in an eyepiece, for viewing diamonds and gems. Focusing distance approximately 25mm. A Jewelers loupe used for Trade Practice must be spherically and chromatically correct.
|
| 50.
|
Melee
|
Small Diamonds less than .20 carat
|
| 51.
|
Mohs Harness Scale
|
The non-linear ten point scale of mineral hardness, keyed arbitrarily to the minerals: talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond.
|
| 52.
|
52. Moissanite
|
A rare crystal in nature. As a diamond simulant, synthetically created moissanite produced by Charles & Colvard is ranking a high 9.25 on the Mohs hardness scale (Diamond = 10). Its double refraction is one of the few differences with a diamond, thermal conductivity is almost equal.
|
| 53.
|
Natural
|
Part of the rough diamond remaining on the diamond, having survived the cutting process.
|
| 54.
|
Needle
|
A long, thin included crystal which looks like a tiny rod.
|
| 55.
|
Nick
|
A notch or nick near the girdle or a facet edge
|
| 56.
|
Off make
|
A poorly proportioned diamond.
|
| 57.
|
Old European
|
Early round cut similar to the round brilliant cut, but carrying a very small table and heavy crown. Not as popular today because it does not return the same brilliance as the modern brilliant.
|
| 58.
|
Open Culet
|
A culet that is larger than necessary and is usually visible to the naked eye.
|
| 59.
|
Pink
|
Pink diamonds: a rare natural fancy reddish color, however radiation treated diamonds (not natural colors) may also have a pink color variation. Treated and irradiated or high pressure-temperature treated pink diamonds are a fraction (2-10%) of the cost of natural pink colored diamonds.
|
| 60.
|
Pinpoint
|
A small rounded tiny inclusion seen at 10X but not large enough to be identified as an included crystal
|
| 61.
|
Pit
|
A tiny opening or indentation on the surface often looking like a white dot.
|
| 62.
|
Points
|
1 Pt. is 100th of a carat.
|
| 63.
|
Polish Mark
|
A groove or scratch left during the polishing process that is confined to a single facet.
|
| 64.
|
Quality
|
Quality in a diamond is based primarily on the cut or make, secondly on color and clarity. Quality and carat weight give the value of a diamond.
|
| 65.
|
Round
|
The most common cut usually containing 58 facets. Also the most brilliant cut, in terms of most efficient use of light to increase brilliance and fire, hence the name 'brilliant'.
|
| 66.
|
Saturation
|
A color's position on a neutral to vivid scale.
|
| 67.
|
Scintillation
|
The display of refraction returned to the viewer from a diamond by either the movement of the observer or the movement of the light source.
|
| 68.
|
Scratch
|
A linear indentation normally seen as a fine white line, curved or straight.
|
| 69.
|
Simulant
|
Also called: Imitation. Any diamond like material, either natural or artificial, which is meant to imitate a natural diamond. Glass, zirconium (Cubic Zirconia - CZ), YAG, GGG, Moissanite etc.
|
| 70.
|
Spread
|
A diamond with a large table and a thin crown height, usually to retain maximum weight.
|
| 71.
|
Surface Graining
|
Surface indication of structural irregularity. May resemble faint facet junction lines, or cause a grooved or wavy surface, often crosses facet junctions.
|
| 72.
|
Symmetry
|
A grade given to a polished diamond based on the proportions of the diamond and the alignment of the facets.
|
| 73.
|
Table
|
The large facet at the top of the crown on a polished gemstone.
|
| 74.
|
Table Percentage
|
The table facet measured between two opposite corners expressed as a percentage of the stone’s diameter.
|
| 75.
|
Treated or Color Enhanced
|
Fancy color treatment: a diamond with a body-color induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing).
Other possible treatments of diamonds are: coating, fracture filling, spot bleaching by laser, HPHT high pressure high temperature whitening, electromagnetic conduction whitening.
|
| 76.
|
Twinning Wisp
|
A cloudy area produced by crystal structure distortion, usually associated with twinning planes.
|
