Most diamonds sold online will be
"certified" which means the diamond has been sent to
an independent gemology laboratory. The gem lab will put the diamond
into a machine called a Sarin which precisely measures certain
characteristics of the diamond such as width, length, table and
girdle size as well as all of the angles created by the cutter.
The diamond will then be examined by a trained gemologist and
assigned color and clarity grades. It is important to remember
that this step in the process is somewhat subjective as there
is no machine or tool that will tell you exactly what color and
clarity a diamond is.
Color is determined by comparing
the diamond to be graded to a control group of diamonds whose
color is known. The gemologist will then assign a color based
on the closest match to the control group, as well as using his
or her experience and judgement.
Clarity is determined by examining
the diamond for inclusions and noting the number, location and
size of the inclusions. The assignment of the clarity grade is
largely determined by the gemologist's experience and interpretation
of each clarity grade.
There are many gem labs in the industry,
the most widely known and respected being the GIA (Gemological
Institute of America). Other well known gem labs include IGI,
AGSL and EGL.
Once the lab has completed the grading
process, a certificate is issued describing the measurements,
weight, color, clarity and other observations that were made.
Most gem labs do not issue appraisals as this may be construed
as a conflict of interest.
