Abrasion - A blemish, such as small nicks along the facet junctions.
A blemish is a small nick along the facet junctions often caused by impact damage. Excessive abrading is often a sign of cubic zirconia instead of a real diamond.
AGS – American Gem Society - One of the leading gemological labs.
American Gem Society is a jewelry association comprised of the top jewelers in the United States and Canada.
Appraisal - An estimation of value of an item, typically for insurance purposes.
Appraisals are often used to help determine the value of diamonds and jewelry. However, they are often overly optimistic in their valuation. Especially when compared to values reported by GIA.
Bearded Girdle - Small hairline fractures running from the girdle into the gemstone.
It is also known as “bearding”. They are small hairline fractures in the edge of a diamond that reduces the value of the Bearded diamond.
Bezel - The large facets (second to the table) on the crown of a diamond.
Black Pique - The black inclusions visible within a diamond.
These are more detrimental to the diamond’s value than white (or clear) imperfections. However, Diamond grading reports will often treat these in the same manner when determining the value of your included Diamond.
Blemish - An imperfection on the surface of a diamond.
A diamond can be internally flawless (IF), even if it has blemishes, including scratches, nicks and abrasions. Blemishes can usually be easily removed by polishing.
Bow Tie Effect - A dark shadow shaped like a bow tie.
This effect is evident in some cuts of fancy shaped diamonds, such as ovals and marquises. The Bow Tie Effect is detrimental to the value of a diamond but not considerably so.
Brilliance - Also known as Brightness of a gemstone.
Brilliance is the effect of all the reflections of white light, both within and external to the diamond. The degree of brightness displayed is correlated to the diamond’s cut grade. Diamonds that are poorly cut will throw off light out of the sides or bottom of the diamond resulting in a less brilliant display. For example, a diamond exhibiting high levels of brightness will receive an excellent grade. While a diamond exhibiting low brightness would receive a Poor cut.
Brilliant Cut - The optimal cut of a diamond so as to provide maximum brilliance.
Bruise - An inclusion (of small cracks or feathers) at, or near, the surface of a diamond.
These are more detrimental to the diamond’s value than white (or clear) imperfections. Despite this, a diamond grading report will often treat white and black inclusions the same for clarity grading purposes.
Canary diamonds - a term commonly used to refer to a yellow diamond.
This is not a technical term you will see on a GIA certificate. GIA utilizes other terms, such as fancy yellow, fancy intense yellow, fancy vivid yellow and fancy light yellow.
Carat weight - The unit of measure to determine a diamond’s weight.
Carbon Spots - Term used to describe black or dark inclusions in a diamond.
The technical name for them is black pique. Black pique is always more detrimental to the value of your diamond than white or clear, as it is more readily noticeable.
Cavity - Is an open imperfection found in a diamond.
Certificate - Labs refer to their grading reports as certificates.
They provide written documentation of the diamond’s natural occurrence, weight, proportions, color grade, clarity grade, cut grade, and other characteristics and qualities of the diamond, including any treatments.
Chip - a section of the diamond that has broken off.
This is very detrimental to the value of the diamond because it requires recutting to return it to its original state. This can lead to the diamond ‘breaking its weight’. This reduces the diamond below a weight level often associated with significantly higher values.
Clarity - determined by the lack of characteristics that detract from it’s clarity
Blemishes, which are surface imperfections and inclusions, which are fully inclosed within a diamond are used to determine the clarity. A grade is determined by the overall characteristics of the stone. More specifically the size, position, number, nature and relief of these are all major factors.
- Size: The smaller an inclusion is the better.
- Number: Generally speaking more is worse than less unless the smaller number are of larger size than multiple smaller ones.
- Position: If an inclusion is under the table, it is more visible and thus detracts more value than ones near the girdle.
- Nature: The type of inclusion can determine the clarity grade. A feather that runs from the crown through the girdle will result in a far worse clarity grade than a crystal in the crown.
- Relief: Inclusions are often white or colorless but they can sometimes be black or even red. The darker the inclusions the worse the clarity rating.
- Clarity Enhancement - These are man-made improvements that increase the clarity grade. Some techniques employed are fracture filling or laser drilling.
Cleavage - a break in the diamond along its plane.
Cloudy - a visual appearance produced by many small inclusions resulting in a cloudy diamond.
A cloudy diamond results in a lower clarity rating and thus a lower valued loose diamond.
Color - The color grade used to determine it’s value.
White diamonds range from colorless with a value of D to light yellow and even brown, falling to Z. This makes up the D-Z color grading range. Once colors go outside of this range you get into fancy color grading. Examples of fancy colors are fancy light yellow, fancy light blue, fancy red, fancy intense blue, fancy vivid pink, fancy dark blue and fancy deep pink. Fancy blue diamonds, fancy red diamonds, and fancy pink diamonds are extremely rare often worth millions per carat.
Color Enhancement - techniques used to improve the color of a diamond.
Methods used to achieve better color are as follows High pressure high temperature treatment, irradiation, color coating, or simply recutting. All of these techniques except recutting will result in a diamond of lesser value in comparison to a non enhanced diamond.
Condition - is the current state of repair.
Mint condition(no chip, abrasions or visible markings), damaged(some chips, abrasions, visible markings), or broken(significant portion is broken or missing).
Crown - the portion of the diamond above the girdle.
Crystal - a bubble like inclusion whose occurrence will negatively affect the clarity grade.
Culet - the facet at the bottom of the diamond.
Most modern cuts have done away with the culet and the existance was deemed detrimental to the value as of recent times.
Cut - the cut refers to the diamond’s proportions.
There are several factors that can affect the cut. The symmetry of the diamond, the cut of the facets all count towards a diamond’s cut grade. These are important because there is an optimal cut that results in the most brilliant diamond. GIA’s cut grades for round brilliant diamonds range from Excellent (EX) to Very Good (VG) to Good (G) to Fair (F) to Poor (P). GIA does not give cut grades on non-rounds or fancy cuts.
Dead - is a diamond that shows no brilliance
A diamond is referred to as dead when it displays now brilliance or lustre, typically as a result of being heavily included. Dead stones are worth considerably less than clean or slightly included diamonds.
Depth - the height of the diamond.
The depth is measured from the top of the table to the bottom of the pavilion or culet.
Depth Percentage - depth (height) of the diamond divided by diameter (or average width).
Diamond - metastable allotrope of carbon.
A precious stone consisting of a clear and typically colorless crystalline form of pure carbon, the hardest naturally occurring substance.
Diamond Gauge - an instrument that is used to measure a diamond
Diamond Grading Report – document that describes a diamond’s features
The report contains documentation of the diamonds natural features. These include weight, proportions, color grade, clarity grade, cut grade, and other characteristics and qualities of the diamond.
Drag Lines - heavy polish lines emanating from a cavity or other surface inclusion.
EGL - European Gemological Laboratory or EGL is a privately owned, for-profit, gemological lab.
Etch Channels - openings at the surface that protrude into the diamond.
Eye-Clean - A diamond with no visible inclusions to the eye.
This is typically found in diamonds of SI quality or better.
Facet - The flat faces on a diamond
round brilliant diamonds have 57 or 58 facets.
Faceted Girdle - a girdle produced with approximately 32 small flat planes.
Fancy Color - colors of diamonds other than the typical white diamond (D-Z)
Fancy colors include fancy yellow, fancy red, fancy blue, fancy green and fancy pink, among others. Fancy color diamonds are typically worth more than those diamonds in the D to Z color range, with blues, greens and reds worth more than any others.
Fancy Shape - refers to diamonds in shapes other than rounds.
Examples of fancy shapes are emerald, radiant, pear, heart, asscher, among many others.
Feather - an inclusion on the inside of a diamond that looks like a small white feather.
Feathers in diamonds detract from the clarity of a diamond and thus lower its value.
Finish - the final detailing or finish of a diamond is comprised of polish and symmetry.
Polish is the final condition of the diamond’s surface while symmetry is the correctness and exactness of the diamond’s shape and facet placement.
Fire -when white light is dispersed into the visible spectrum.
Diamonds with larger tables tend to show less fire. However, the right combination of lower girdle facet length, crown angle and pavilion angle can still result in a fairly high level of fire.
Fisheye - the dark reflection of the girdle within a shallow diamond.
Poorly cut diamonds (i.e. not deep enough) are worth less than a well proportioned diamond of a similar weight, color and clarity.
Flaw - an inclusion, such as a blemish, fracture or cavity.
Flawless - a diamond that has no inclusions.
Fluorescence - The light shown when exposed to ultraviolet light.
A diamond with strong fluorescence can appear cloudy and thus detracts from its value. However this is not seen as much of a problem with diamonds of color J or less.
Four C’s - common term for the four primary characteristics of a diamond.
Four primary characteristics of a diamond – carat, cut, color and clarity.
Fracture - a major inclusion in a diamond that looks like a crack.
Fractures are detrimental to a diamond’s clarity grade and can even lead to a diamond cracking or breaking entirely.
GIA (The Gemological Institute of America) - one of the leading gemology labs
GIA is a nonprofit gem research institute dedicated to provide corporate & company gem education in the field of gemology & jewelry arts.
Girdle - the usually narrow area between the crown and the pavilion
The girdle can be classified as extremely thin all the way up to extremely thick. When a girdle is extremely thin it can be seen as a point of weakness.
Graining - lines or curves that appear whitish, colored or reflective.
These lines are caused by irregularities in the crystal growth.
Hardness - The measurement of resistance to pressure, avoid deformation.
Hardness is measured on the Mohr’s scale of hardness. Diamonds rate on the very high end at a 10, the hardest rating.
HPHT - High Pressure High Temperature treatment process.
HRD - Is a Belgian based diamond lab.
HRD Antwerp’s primary shareholder is the Antwerp World Diamond Centre (AWDC). The AWDC is a private foundation established in 1973 as the Hoge Raad voor Diamant (HRD) or Diamond High Council and represents the Belgian diamond industry.
Hue - A color or shade
The attribute of a color by virtue of which it is discernible as red, green, etc., and which is dependent on its dominant wavelength, and independent of intensity or lightness. In colored diamonds they are often given two colors. For example, a diamond might be a fancy yellowish, brownish orange. The latter color is the most dominant hue and the one that affects the value the most.
IF - Clarity grade of Internally Flawless (only very minor surface inclusions allowed).
IGI - International Gemological Institute.
A privately-owned gemological lab with offices in Antwerp, Dubai, Hong Kong, Los Angeles, Mumbai, New York, Tel Aviv, Tokyo, and Toronto, among other cities.
Imperfection -A generic term used to define inclusions.
Inclusion - an internal clarity characteristic in a diamond
Examples of inclusions are as follows: crystals, needles, pinpoints, clouds, graining, twinning wisp, laser drill holes. The more inclusions found in your diamond the lower the clarity grade. If laser drill holes are found those are even more detrimental. Examples of inclusions that extend out of the diamond are as follows: the bearded girdles, bruises, cavities, chips, feathers, indented naturals and knots.
Irradiated Diamond - radiation exposure used to change the color of a diamond
Irradiating a diamond may improve its color but it also has the unintended consequence of negatively impacting the diamond’s value.
Knot - a transparent crystal that extends to the surface of a diamond.
Laser Drill Hole - A hole created by using a laser.
This is a technique used to remove black pique by creating a whole to the pique and then bleaching it with acid to improve the diamonds clarity. This treatment negatively impacts the value of diamonds.
Laser Inscription - An inscription on the diamond’s girdle that contains the lab grading report or certificate number.
This has no impact on the diamond’s value, but makes it easier to identify the diamond.
Lizard Skin - A wavy surface area on the diamond that literally looks like lizard skin.
Loupe - handheld magnifying glass used to inspect diamonds.
A standard loupe is 10X magnification but more powerful 12X, 14X, etc are available.
Lower Girdle Facet - Triangular facets just below the girdle.
Luster - the quality of shining by reflecting light from the surface of a diamond.
Melee - Diamonds of less than .20 carats used in
Melee can be used to frame a center stone (pavé setting) or used on its own.
Natural - Also known as Indented Natural.
The natural can be a portion of the original surface (or skin) of the diamond (rough) or an opening left when a surface-reaching crystal is worked during polishing.
Needle - An elongated, thin crystal inclusion that looks like a needle.
Nick - A small notch on a facet junction
Pattern - Contrast and arrangement of the light and dark areas of the diamond.
Pavilion - The underside of the diamond between the girdle and the culet.
Pavilion Angle - the angle formed by the plane of the pavilion facets and the girdle.
Pinpoints - Small crystals that look like dots under 10x magnification.
Pit - a small opening that looks like a white dot.
Point - one one-hundredth of a carat (1/100th).
Polish - The overall condition of the diamond’s surface.
Diamonds take a better polish than any other gemstone due to its hardness. However, as result it must be polished with another diamond. Polish is graded on a scale of Excellent to Poor and each tick down in grade (caused by abrasions, nicks, scratches, etc.) reduces the value of the diamond.
Polish Lines - Fine, parallel grooves and ridges remaining after the polishing process.
Heavy polish lines emanating from a cavity or other surface inclusion are known as drag lines.
Rough Diamond - a diamond that has not been cut or polished.
Scintillation - A combination of the sparkle and pattern of a diamond.
Sparkle is the appearance of spots of light that flash as the diamond moves. Pattern is the arrangement and contrast of the bright and dark areas of the diamond resulting from light reflections.
Scratch - A dull, thin white line on the diamond.
It can be removed by repolishing but the diamond may lose some weight.
Shape - diamonds are cut into numerous shapes, with the most popular being round brilliant.
Also referred to as fancy cuts, shapes include round, marquise, cushion, emerald cut, pear, heart, trillion, radiant, princess cut, Asscher, oval, Old European cut, old mine cut, baguette, half moon, among others.
Sparkle - the appearance of spots of light that flash as the diamond moves.
Symmetry - Symmetry is the exactness of the shape and placement of the facets.
A diamond should look symmetrical. It should be round (as opposed to off-round), the table should be in the middle of the crown (i.e. you should see equal amounts of the pavilion each side of the culet when viewing the diamond through the table), the culet should be in the middle of the table (i.e. the culet should be centered on the pavilion), the girdle should be flat (as opposed to being wavy), among other symmetries.
Synthetic Diamond - A man-made synthetic diamond
It’s created by using high pressure high temperature (HPHT) or lab grown using chemical vapor deposition (CVD) process.
Table - the large facet at the top of the diamond.
Table Percentage - For a round brilliant cut, the average width of the table as a percentage of the average diameter of the diamond. For fancy shapes, it is the width of the table as a percentage of the width of the entire diamond.
Treated Diamond - An altered diamond to change its clarity or color.
Twinning Wisp - A group or series of clouds and/or pinpoints that form within a diamond’s growth plane.
VS - clarity grade of Very Slightly Included (VS1 and VS2).
VVS - clarity grade of Very Slightly Included (VVS1 and VVS2).