Everything you need to know on Certificates
All rare and natural untreated gemstones must therefore have an internationally recognized gemmological certificate. From laboratories like GIA, SSEF, Gübelin or GRS just to mention the best. The certificate will confirm not only the origin but also the absence of treatment.
For Natural colour diamonds, there should be no colour or purity enhancements. If there are, this must be made clear from the beginning, as it will severely reduce the price of the diamond.