A gemstone lab report, often called a certificate, states what a stone is, whether it has been treated and, from some labs, where it comes from. Those lines can move the price of a ruby, sapphire or emerald more than its size. This page gathers every Carat Brief guide to reading them.
Updated November 8, 2026.
Reading and Verifying a Report
One stone can carry several reports. The Romanov Sapphire is offered with four, from SSEF and Gübelin, and their wording differs: see The Romanov Sapphire at Sotheby's Geneva.
Heat Treatment
Oil and Resin in Emerald
Glass Filling in Ruby
Why It Matters for Price
Treatment and origin are priced stone by stone, and we found no reliable public multiple that applies across the market. Our colored gemstone price guide shows the named sales behind each number.
FAQ
Is a gemstone certificate the same as an appraisal? No. A lab report describes the stone. An appraisal puts a value on it, and labs such as GIA do not give one.
Which lab is best for colored stones? It depends on the stone and the market. Our comparison of SSEF, Gübelin, GRS and GIA sets out what each one reports.
What does "no indications of heating" mean? That the lab found no evidence of heating. It describes what the lab observed, not a guarantee.
The lab language behind the prices.
Auction results and the report lines that move them. Every Tuesday.
Carat Brief is editorial and is not investment advice.