Beyond "cut" grading: AGS vs GIA

[decisively_unsure]

Yes, cut and overall proportions are king, but I have seen some evidence that GIA "very good" polish can get reported as "ideal" AGS polish. How do the labs compare in your experience when it comes to symmetry and polish grading, colour too? Seems to me that clarity grading is the same across the labs.

 

[Texas Leaguer]

Re: Beyond

Yes, cut and overall proportions are king, but I have seen some evidence that GIA "very good" polish can get reported as "ideal" AGS polish. How do the labs compare in your experience when it comes to symmetry and polish grading, colour too? Seems to me that clarity grading is the same across the labs.

AGS attempts to stay in synch with GIA grading in virtually all ways other than their light performance component of cut grading. There is always anecdotal evidence of one lab being "softer" than the other in some respect or another, but companies that have a large sample size using both labs will attest that they are essentially equivalent, given the inevitable and accepted variances largely due to the human element. In the last few years GIA has had some challenges maintaining consistency within their own growing collection of laboratories, which in turn presents challenges for labs that are trying to stay in synch with them.