GIA vs. IGI: Which Grading Report Should You Trust?

Grading reports exist to give buyers an independent read on a stone's cut, color, clarity and carat weight — but not all labs grade to the same standard, and the gap matters more on some attributes than others.

GIA is generally considered the strictest and most consistent lab, particularly on cut grade and color. IGI grading has historically run a shade more generous, especially on lab-grown stones, which is part of why lab-grown diamonds with IGI paperwork are often priced lower for a nominally equivalent grade.

For natural diamonds over 1 carat, a GIA report is worth paying a premium for if you plan to insure, resell, or simply want the tightest possible grading tolerance. For lab-grown stones, where resale value is a smaller factor, IGI is a perfectly reasonable and more common standard.

Editorial disclosure: this guide reflects our independent research and is not sponsored by any retailer named in it.