Labs grading mistakes are a diamantaires favorite topic of conversation; are mistakes myths or reality? We aim to find out.
If major labs give the same diamond 2 or more grade differences, this is more than a borderline difference of opinion. We want your help to find examples (like this one).
We will send stones anonymously to other labs if volunteer experts believe other major labs would give more than one grade difference. Where there are two or more color, clarity, cut or finish grades difference the results will be published.
Labs can use different methods and processes. For example should color grading be done with, or without UV emitting lamps? Is back light or is front light more appropriate for clarity grading? However, both markets and consumers expect “standardized” results.
We hope examples of bad grading will be rare. A lot of examples, like the stone shown here, should lead to a lowering of prices for diamonds graded by “soft labs”. Manufacturers and dealers will use those labs less. Soft labs should then standardize their processes or loose business.
Is this an H SI2? Or J I1?
(click on each image to see larger picture)
A 1ct J I1 is worth about 45% less than an H SI2. Even though the market discounts EGL stones, compared to GIA, the average price difference is still 30% for stones on offer with those certs and grades.
In a 2004 lab survey, conducted by Pricescope.com, none of 16 stones was graded the same for color and clarity by all 3 labs (AGS, EGL-USA & GIA). But B-2-B markets efficiently priced the stones at the same prices with their different reports; the markets seem to work because none were 2 grades off.
Why do it? Who benefits?
- Improve all our reputations.
- Every stage of the pipeline suffers.
- Consistent grades means improved distribution.
- More confident consumers will lead to sales. growth.
- Grading costs can be more than cutting costs.
- It is costly & inefficient to challenge “harsh” grading.
- Reduce the number of labs stones are sent to.
- Free up skilled staff.
- Turn inventory faster.
What can you do to help?
Report stones by sending their details to the e-mail address below (remain anonymous if you wish). Details will be posted on a closed private Intranet Forum, so that no labs are alerted. The volunteer experts (independent of major labs) may want more information, or the stone might be needed for further testing. If the committee believe a 2 grade error has been made, the diamond will be sent anonymously to various labs (and possibly back to the same lab). If a stone has 2 grades (or 3+ AGS cut grades) difference, the reports will be published on www.Pricescope.com and made available to news media and trade magazines.
Donations to cover Lab fees, insurance and shipping costs will be gratefully accepted. Donors names can be included (if you wish) in all press releases. We also need volunteer experts from the main diamond centers; please contact us: