To demonstrate what's possible, let's use our 2.12ct F/Internally Flawless as an example.

When we consider a diamond for purchase, the cutter, or broker, will drop the diamond at our office, and leave it for a period of time, while we mull over it's potential. The diamond comes in a parcel paper with a sticker showing the pertinent GIA info. I can see the depth, table, polish, symmetry, etc...
As you'll see, there's a vital piece of info not there- but I know this was not intentional- that info is not on any of these stickers. The sticker, by the way, is not printed by GIA, rather a software program the cutter has- which spits out the info from the GIA report onto a sticker.

When we decided to purchase the diamond for our stock, and the GIA report itself was delivered, we got a big surprise.
The GIA report was from 1998. In this case, that was a concern- especially considering the importance ( high value) of this rock. For this reason, we sent the diamond back to GIA for a new report.
They re-examined the diamond. The color and clarity stayed the same F, Internally Flawless. The symmetry was still rated Excellent, however the polish was now considered "Very Good" as opposed to "Excellent".
The polish and symmetry were a large part of the motivation to purchase the diamond.
As a diamond dealer, on the New York market for over 30 years, we know who we're dealing with- I had no doubt whatsoever the cutter would stand behind the stone. He did.
The reason for the downgrade on Polish was a slight abrasion which had somehow occurred over the years since GIA first looked at it. Upon our request, GIA gave us a detailed diagram showing where the abrasion was.
The cutter stood behind the stone by offering to either take it back, or fix it. We chose to allow him the opportunity to repair the diamond- there was little risk as we could still back out if the results were not optimum.
Talk about a great job! He was able to repair the diamond, and not even loose one point of weight!
AS you can see- the measurements changed ever so slightly- but not a point of weight lost. Remarkable.
Measurements before repair- 7.22 x 7.15 x 4.84 mm
After repair-: 7.16 x 7.12 x 4.84 mm
There's a number of things I take away from this story. One thing is a no brainer- there's no way to overstate the importance of dealing with someone who stands behind the goods.
But also how the value of desirable diamonds has been consistent for a long time in our lifetimes.
It bothers me
not at all that the diamond was originally cut ten years ago-and may have been owned by someone else. That fact makes no difference in it's value.