Glossary
Below are a list of key terms to help clarify the commonly used words, phrases and abbreviations used in the diamond trade. One might hear these from your jeweler or from other diamond collectors.
Appraisal – This is a service performed most often by jewelers and other experts. It serves to give the owner of a gem or piece of jewelry the approximate retail value of the item in the event that they ever need to replace it. It should not be done by the source of the item because an independent appraisal is less likely to favor the original retailer’s price to an unfair level. Most often used for insurance purposes, but one should have appraisals done every few years to keep current on the item’s value.
Brilliance – Term used to describe the way white light reflects from a diamond.
Brilliant Cut Diamond – The most popular modern cut for a diamond, generally features 57 facets unless there is a cutlet, in which case it features 58. Chosen because it emphasizes brilliance better than any other cut and also because a great deal of mathematics has gone into its design.
Carat – Standard unit of measurement to determine the weight of a diamonds. One carat is equal to 100 points ( 2 milligrams per point), 1/5 of a gram (0.2 g) or 1/142 of an ounce (0.007055 oz).
Cavity – An inclusion that is an opening into the stone. Can vary in depth.
Clarity – A judgment about a diamond formed based on the number and type of inclusions within the gem. Those stones which are free from blemishes and inclusions are worth more. IF and F are the highest possible grades of clarity.
Cleavage – An inclusion that can be caused by inherent internal strain or a heavy blow struck in parallel to one of the crystallographic planes within a diamond. The cleavage can sometimes reach the surface of the diamond.
Cloud – These inclusions are generally in clusters and give a cloudy appearance to the diamond’s interior.
Crown – This is the area above the girdle on a diamond, includes the table as well as all facets between the table and the girdle.
Crystal – A inclusion of a mineral trapped within a diamond.
Culet – The flat facet at the bottom of a diamond, always the smallest. On a round cut diamond this is the 58th facet.
Cut – The overall proportions which a diamond is shaped into through symmetrical facets created by a skilled diamond cutter.
Depth – This is the distance, measured in millimeters, from the crown to the culet of a diamond.
Dispersion – As white light is broken up by entering a diamond, a rainbow of colors show called dispersion.
Eye Clean – Term used by gem experts to express the fact that a stone has no inclusions which can be seen without magnification.
Facet – The polished plane or ‘face’ that is cut onto a diamond.
Feather – Fracture included in a diamond that resembles a pale feather.
Fire – The spectrum of colors given off by a diamond as a result of dispersion.
Fracture – Break, chip or other division within a diamond that is not going in the same direction as the cleavage plane. Often appears like a splinter or staircase.
GIA – Abbreviation for Gemological Laboratory of America, a foremost lab for the study of diamonds and other gems. Known for their Diamond Grading Reports.
Girdle – This is the widest part of a diamond that runs the length of its circumference. It forms a band that can be polished, faceted or unpolished.
Inclusions – Naturally occurring detractions to a diamond’s value and beauty. Could be: feathers, clouds, pinpoints or crystals.
Loupe – A magnifying glass used by jewelers and usually set to 10X setting during the examination of a diamond.
Pavilion – This is the portion of a diamond that is beneath the girdle.
Pinpoints – Tiny inclusions within a diamond.
Polish – This is graded from poor to excellent. It is the finish of the diamond applied by the cutter.
Scintillation – The sparkles that emanate off a diamond when the viewer moves while observing the jewel.
Shape – The shape of a diamond that is used in jewelry. Most common are: Emerald, Oval, Heart, Marquise, Princess (also called Radiant), Round or Trillion. Other shapes can be created by different diamond companies.
Symmetry – Graded from poor to excellent, this value measures the proportions of the diamond as they relate to each facet cut into the stone.
Table – The largest facet of a diamond, located at the top of the stone. The majority of light enters and exits through this facet.