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Lab-Grown Diamond Certification Explained: GIA vs IGI | House of Diams

A grading report is one of the most important documents to understand when buying a lab-grown diamond. It independently identifies the stone and records information that helps you understand exactly what you're purchasing. IGI and GIA are two major gemological laboratories used for lab-grown diamonds, but their current reporting systems are not identical. This guide explains what an IGI or GIA report can tell you, how their approaches differ, what changed with GIA's lab-grown diamond assessments in 2025, how to verify a report number and laser inscription, and which details you should check before buying a certified lab-grown diamond.