A few weeks ago, we sent seven stones to the GIA in Carlsbad for certification. Six had our own “Jogia Grading System” certificates and one had a DCLA certificate.
I sent them there, not because I thought the grading was wrong, but because GIA certified diamonds generally attract a premium over other stones.
Cost & Time of GIA vs Australian Labs
In the past, we’ve used DCLA, and more recently Auscert for certification of stones that don’t have certs. However, when doing the sums, the cost difference of GIA certification vs Auscert is minimal, and with this case was even cheaper.
For seven stones and laser inscription, Auscert would have cost $840 ($120/stone) + $26 shipping = $866. For six GIA Diamond Dossiers and one full grading report, the cost was US$447 + $250 shipping = $788. These equations however don’t take into account the fact we have insurance to and from the USA included in our jewellers’ block policy, so really, we should be factoring that into the equation.
Time is another important factor. GIA took three weeks, including one week shipping. Local labs usually take 1-2 days + 2 days shipping. If these were “fast moving” stones, like rounds or princesses, there would probably be an opportunity cost involved in shipping the stones to the GIA.
The results were hardly surprising, and no grade was out by more than one colour and clarity grade:
|Shape||Original Grader||Original Grade||GIA Grade||Upgrade/Downgrade?|
|Emerald||JGS||0.60 E/VS1 + Med Blue Fluoro||0.60 F/VS1 + Med Blue Fluoro||Downgrade|
|Emerald||JGS||0.75 F/VS2||0.75 F/VS2||Same|
|Emerald||JGS||0.93 E/VS2||0.93 E/VS1||Upgrade|
|Asscher||JGS||0.63 F/VS2||0.63 G/VS2||Downgrade|
|Asscher||JGS||0.81 E/VS2||0.81 D/SI1||Slight Downgrade Based on Rap|
|Asscher||JGS||1.01 F/VS2||1.01 F/VS2||Same|
|Heart||DCLA||0.71 E/VS1||0.71 F/VS1||Downgrade|
As you can see, the results were a mixed bag. The worst discrepancy was the 0.81 asscher cut going from a E/VS2 to a D/SI1. Whether you can call it a downgrade is questionable as the stone is eye-clean and now has a colour D.
- Diamond grading is subjective.
- GIA certification isn’t expensive.
- Results seem to support this survey, in so far as GIA is tougher on colour than clarity.
- No real conclusions can be made regarding which lab is better.
- I don’t have a rap sheet in front of me, but I would imagine the “list value” of the six JGS stones increased as the two smallest stones were downgraded and the second biggest stone was upgraded by one colour grade.
- The price of these stones will be increased by 10% 🙂