Lab report

A lab report is an independent laboratory's written record of what a stone is: species and variety, weight to the hundredth of a carat, measurements in millimetres, the treatment observed, and often an opinion on geographic origin. It is not a valuation. It is not a promise that the stone is beautiful, and a fine report can sit on a dull stone. What it does is fix identity and treatment at a point in time, so that price can be argued about honestly. For anything unheated, anything sold on origin, or any ruby, sapphire or emerald of more than a carat or two, the trade expects one.

On a lab report

Layouts vary. The operative lines do not. Look first for the treatment statement. GIA writes "no indications of heating" or "indications of heating"; SSEF and Gübelin use near-identical wording, and for emerald add a line on clarity enhancement; GRS writes "no indication of thermal treatment" and marks heated stones with an H code; AIGS and Lotus spell it out in plain words. Origin appears as "Origin: Burma (Myanmar)" or "Sri Lanka", sometimes with the word opinion attached, because that is what it is. Then find the report number and the date. GIA, Gübelin, SSEF, AIGS, GRS and Lotus all let you check a number online, and a report that cannot be checked is paper. Some houses add colour terms such as "royal blue" or "pigeon's blood"; those belong to that laboratory's own scale.

Read the report against the invoice and against the stone. Weight, measurements and any photograph should agree, and the seller's description should claim nothing the paper does not. A report from a decade ago records the stone a decade ago; an emerald may have been re-oiled since. Where the documents diverge, stop, and do not go on until the gap is explained or the stone has been re-certified.