Glossary of diamond terms used on this site
There are 146 entries in this glossary.All
| Term | Definition |
|---|---|
| AGS Ideal 0 |
The term "AGS Ideal 0" refers to a diamond rated by the AGS Laboratory as having Ideal Polish, Symmetry, Proportions and Light Performance. The AGS Ideal 0 grade can only be assigned by the AGS Laboratory. |
| AGS or AGSL |
The American Gem Society Laboratory (AGSL) |
| ASET |
The ASET Scope was developed by the AGS Laboratory and is used by them to grade optical symmetry within a diamond as part of their Light Performance rating system. The ASET™ is similar to the Ideal Scope and its counterparts in that it uses filtered light to provide the viewer with insight into the optical symmetry of the diamonds, however that is where the two devices cease to be similar in concept or use. |
| Bearding |
Bearding or "dig marks" are small feathers or breaks along the girdle edge of a diamond that are caused by the bruting process. |
| Bright Field Microscopy |
Bright field microscopy is the most common technique used when using a microscope in the diamond grading process, it involves illuminating the diamond from below and observing the specimen from above. |
| Brilliance |
Brilliance is the amount of white light or white sparkle directed back towards the viewer by a diamond; the degree of brilliance exhibited by a diamond is controlled by the angle of the diamond cut, as well as the angle of observation and the location of the person viewing the diamond within the room. |
| Bruise |
"Bruise" is a diamond clarity term used to describe the presence of feathers which radiate from a point where the stone was hit. |
| Bruted |
Bruted is a term used to describe a girdle edge which has been left unpolished or unfaceted after being cut. The process of beating two diamonds against each other by spinning them in close proximity is known as bruting the girdle edge and leaving a girdle edge unfinished after that process leaves it bruted. A girdle edge which has been left bruted will resemble frosted glass when viewed through magnification. |
| Cert |
The slang term "Cert" is an abbreviation for "Certificate" which refers to what is correctly known as a "Diamond Grading Report" or "Diamond Quality Document" which is a document issued by a diamond grading laboratory describing the characteristics of a diamond. It is not accurate to refer to a diamond grading report or document as a "Cert" or "Certificate" because the diamond grading laboratories do not actually certify the stone's quality. |
| Certificate |
The term "Certificate" refers to what is correctly known as a "Diamond Grading Report" or "Diamond Quality Document" which is a document issued by a diamond grading laboratory describing the characteristics of a diamond. It is not accurate to refer to a diamond grading report or document as a "Cert" or "Certificate" because the diamond grading laboratories do not actually certify the stone's quality. |
| CGL |
Central Gemological Laboratory - Japan / Antwerp |
| Chip |
With regard to "clarity characteristics" a chip is a mark or flaw located on the surface of the diamond made by the breaking off or gouging out of a small piece. This is often confused with the term "diamond chip" which refers to an extremely small diamond. A chip in the surface of a diamond most often occurs as the result of a slight impact. Most chips are minor and can be removed from the surface of the diamond by re-cutting or polishing the gem with a minimal loss of weight. Extensive chips may require that the entire diamond be re-cut which usually results in a more substantial loss of weight, such as a third to a half of the carat weight or more. |
| Clarity |
The "Clarity" grade of a diamond refers to the degree to which inclusions within the diamond are visible to a trained diamond grading using their eyes and 10x magnification. In addition to the general visibility of the inclusions, the location and extent of the inclusions play a factor upon the clarity grade of a diamond. |
| Clarity Characteristic |
The “Clarity Characteristics” section on gemological lab reports indicates the type of inclusions contained within the diamond described by the lab report. The term "clarity characteristic" refers to the inclusions within a diamond which are the basis for the clarity grade assigned to the diamond. |
| Clarity Enhanced |
"Clarity Enhanced" refers to a process of diamond treatment more accurately referred to as "Fracture Filled" which often involves using a laser to drill to the location of an inclusion within a diamond to reduce the size and/or visibility of the inclusion and then filling the drill hole or inclusions such as fractures with a glass-like filling agent. The filling agent has a refractive index close to 2.417 which is the refractive index of diamond which makes it difficult to detect the treatment. However a color-flash effect is created due to a juxtaposition of the two different materials. The filling can be damaged or removed by exposure to heat higher than 1400 degrees or acids. Since the treatment is not permanent, the clarity grade of the diamond is not reliable and for this reason many gemological laboratories refuse to grade diamonds which have been fracture filled. Federal Trade Commission guidelines require that disclosure be made in writing to consumers who purchase a fracture filled / clarity enhanced diamond. |
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ECB Exchange Rates on September 06, 2010. |
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