Certificate mismatch

A certificate mismatch is any disagreement between a stone and the report that travels with it: weight, measurements or inclusions that do not correspond to what sits in the paper. The causes run from innocent recutting through clerical error to fraud. Recut a stone after the report date and it loses a few points and its measurements shift. Transpose two digits at the front desk and the same thing shows on paper. And then there is the third case, in which a genuine report from a respected house has been married to a different stone altogether, because a real document lends its authority to whatever sits beside it. The paper looks identical in all three.

In practice

The defence is dull, and it works. Start with the report number. GIA, Gübelin, SSEF, AIGS, GRS and Lotus each keep an online record of what they issued, weight and measurements included, and checking takes a minute. Then put the stone on your own scale and under your own gauge. Reports give weight to two decimals and dimensions to a hundredth of a millimetre; the numbers agree or they do not. Where the house has printed a photograph of the stone or plotted its inclusions, go looking for the same crystal, the same feather, in the same place. A recut stone fails on weight and size and passes on inclusions, which is an honest story with a re-issue at the end of it. A stone that fails on all three has, in our experience, never met its report.

Any gap you cannot account for is a reason to stop until re-certification settles it. Dealers with nothing to hide send the stone back to the laboratory without being asked twice. Dealers who want to debate a few hundredths of a millimetre have told you what you needed to know. Get the report number before anything ships, and check it the same day.