GIA doesn't have much to do with that beyond the cases they're brought in to help identify origins of rough diamonds. Regrading old stones in the pipe, recutting of old stones, you can't ever REALLY know for sure, honestly. Other than Canadian-mined diamonds, there's sometimes no real way to prove a stone is non-conflict. The Kimberley Process keeps the vast majority out of the supply, 99+ percent, supposedly. But since it's up to each country's government to certify nothing was tampered with, you have to hope no one within those governments is corrupt and that each parcel and diamond is properly confirmed of that. I would like to think that since these countries depend on the money these exports generate, that they would not risk a single booboo in that process though, and that they keep their hands clean.
Regarding the comment on the appraisal::: who provided this "appraisal" valuation? The jeweler or a third party appraiser? Often the seller will provide an inflated value to make the buyer feel they got an incredible steal of a deal. What you want your appraisal valuation to show is what your ring would realistically cost to replace if you had to go elsewhere to do so. You would not likely need $30,000 to replace that ring, but maybe $20,000 since pricing varies and you have to sometimes deal with supply and pricing increases in the market.
