If you are considering investing in a diamond, you require two guarantees on the part of any merchant : a laser-engraved certificate number (in the case of a diamond), as well as laboratory sealing of the stone (for all stones). The latter condition will enable you to detect a fraud without any possible doubt.
Laser engraving is not to be overlooked. Once the stone is mounted in a piece of jewellery, you will be able to recognise your gem thanks to this engraving by using a simple magnifying glass (there is no need for a microscope). The certificate number must be preceded by the company logo of the laboratory that performed the appraisal, and of course, the certificate should mention the engraving.
You will find all the information you need to confidently make your purchase by following the links of the only three laboratories recognised by the diamond trade :