How consistent are GIA certifications?

[Razor488]

I was at a jeweler today and he was telling me that he often disagrees with GIA certs on diamonds... He had an incentive to say that because he wants to add value and has to compete with these online sellers.

Are GIA certs pretty consistent with their ratings?

 

[Texas Leaguer]

I was at a jeweler today and he was telling me that he often disagrees with GIA certs on diamonds... He had an incentive to say that because he wants to add value and has to compete with these online sellers.

Are GIA certs pretty consistent with their ratings?

GIA invented the grading system that most of the labs use today. They have trained graders grading diamonds all day long according to established standards, using state of the art equipment, carefully vetted master stones, and redundant multi-level quality control.

There is always a small amount of variance in grading by the top labs. This is due mainly to stones that are right on borderlines and because human grading is involved in most cases. In general, GIA is considered very consistent.

What makes this particular jeweler feel that GIA certs often don't meet his standards? What are his credentials? What is the quality of his lab where he does his grading?

Most jewelers will say they have occasionally seen stones with certs they disagree with. A jeweler that says he "often" disagrees with GIA is likely either not a skilled grader himself or is selling something other than GIA diamonds.

 

[Rockdiamond]

Hi Razor,
From my perspective it could be a few things....
Best case- the seller is very familiar with GIA grading practices.
Many people here on Pricescope have expressed qualms about GIA's cut grade for example. They advise further investigation beyond the GIA grade.
In my position, buying from cutters with the stone in front of me, a common selling tactic involves attacking the GIA grade
For example the seller might say "it's an amazing VS2- it should have gotten VS1."
or
"It's definitely a J - even though GIA gave it a K. I re-submitted twice"
There are definitely borderline stones that might get VS1 on one day and VS2 the next.
There's broad agreement that hands on assessment is the best way to really evaluate a diamond.
So a seller could use the point that they hand select the best stones to add value.

Worst case: The seller is attempting to pull the old "GIA is no good, so let's use some other lab" routine.....run, do not walk away from that one unless the other lab is AGSL.
Other than that, please watch out.

 

[Garry H (Cut Nut)]

Ask him how many stones he has available for sale where GIA was too soft
(I have some from time to time)