For expensive pieces, a GIA or IGI report is the gold standard. However, be wary of "in-house" appraisals or certificates from labs you’ve never heard of; these often inflate the "estimated retail value" to make a price look like a bargain.
If you’re looking to build a collection without paying retail markups, here is how to navigate the marketplace like a pro: 1. The "Too Good to Be True" Filter buying jewelry on ebay
If you see a "2-carat natural diamond" for $150, it isn't. eBay is flooded with (like cubic zirconia) and lab-created stones labeled in ways that mimic natural gems. For expensive pieces, a GIA or IGI report