Diamond Grading Certifications
GIA Gem Trade Laboratory
The Gemological Institute of America are the creators of the International Diamond Grading System. The definition of the 4 C's as the world knows it today was set by GIA. Besides conducting extensive scientific gemological research and developing gemological professionals through education, GIA provides the jewelry industry with GTL Reports. The GIA Gem Trade Laboratory Report for diamonds, often referred to by many, as a GIA Certificate is undoubtedly the world's most reliable, accurate, recognize and valuable diamond grading report. This report provides great details on the diamond and offers a diagram of internal and external characteristics or flaws. It is the finger print that uniquely identifies that particular diamond and which could be used later to verify that diamond:..("Rejection" Class).
Because G.I.A. grades only natural diamonds, those who purchase diamonds with a G.I.A. Diamond Grading Report will be assured that their diamond will not be a synthetic (man-made) or clarity enhanced (fractured filled) diamond. These are the two prevalent problems facing the consumer in this high-tech era.
Every diamond GTL grades gets analyzed by a Sarin Diamond Proportion Analyzer. This information currently is not provided in the GTL Report but is kept with GIA as additional identification information on that particular diamond. For those who are pursuing ideal cut diamonds and are interested to know the crown angles, pavilion angles, and other proportional details, one must simply ask the vendor for a Sarin Diamond Proportion Report. All vendors that are serious about selling ideal cut diamonds have this report.
Don't be enticed to accept another laboratory report in lieu of GIA because it provides addition proportion information. Rather stick with GIA GTL Report for gemological accuracy and request a supplemental Sarin Diamond Proportion Report. This way you will never get the wrong color, clarity, polish, symmetry and fluorescence rating. The following is the breakdown of the GIA GTL Report, line by line.
AGS Laboratory Report- Diamond Quality Document
The American Gem Society gemological laboratory, founded by GIA founder Robert Shipley, grades diamonds according to GIA standards. Fewer diamonds are available with AGS diamond quality reports. AGS quality reports are popular with retailers that prefer to have the full proportion measurements including the crown angles and pavilion angles disclose to their customers.
The diamond quality report provides a complete analysis of color, clarity, and diamond proportion. The diamond quality report also provides a carefully drawn plot which illustrates the exact position, size and shape of every external blemish and internal inclusion a diamond possesses.
The AGS is the only gemological laboratory that assigns the cut grade on a numerical scale between 0 and 10. The AGS system of defining cut grade is modeled after the Tolkowsky theoretical ideal brilliant which is a standard of facet angles and ideal proportions that were calculated mathematically by Marcel Tolkowsky in 1919. It also carefully considers the aspects of symmetry and diamond polish in the assignment of a cut grade. An ideal cut diamond is assigned AGS cut grade 0. Small incremental proportion deviations from the ideal cut model assign the next higher numerical cut grade. Cut grades 1 and 2 are still considered excellent.