hi mouldy.
will start search.heres number 1
http://www.bridaldiamond.com/info/how-to-read-gem-cert.cfm
. Which Gem Lab issued the diamond grading report?This is a crucial and often overlooked factor in the evaluation of your diamond. We’ve been buying diamonds for over 40 years and can say without reservation that
some labs are very strict in their Color and Clarity grades and some labs are soft in their grades. When it comes to Cut, the numbers speak for themselves. However, Color and Clarity are subjective to a gemologist’s opinion. A single bump in either Color or Clarity grade will increase the market value of a 1 carat diamond by about 10% and a 2 carat diamond by about 20%.
If you view a diamond in our inventory that is priced substantially less than another diamond with similar Weight, Cut, Clarity and Color standards, take note of the lab that issued the grading report.
The most reliable and strict grading reports are issued by
AGS and GIA. This does not mean that buying a diamond with a report from another lab is a bad deal. You should simply be aware that the Color or Clarity may be a grade lower than stated, and evaluate the price accordingly .
If you find what appears to be an extraordinary value on a stone evaluated by EGL, IGI, HRD, or AIG, we invite you to call our diamond buyer, Andy Marcum at (800) 418-7678. He will evaluate the stone personally and issue an informal opinion, at no cost, that is probably more representative of the true value of the diamond you have in mind. It may be a great bargain, even if the gemlab certificate overstates Color or Clarity.
There are several articles in the trade press that document the differences in grade ratings from various labs. You can
read more here, or ask any trusted local jeweler about their opinion. The industry consensus is broad and in general agreement about the reliability of grading from different gem labs.