Hanadama
A Japanese certification for the top tier of Akoya pearls, issued by an independent laboratory rather than a seller.
Hanadama means flower pearl. The certificate is issued by the Pearl Science Laboratory in Japan after testing an assembled strand.
It measures nacre thickness, lustre, surface and colour, and it applies to the strand as a whole rather than to loose pearls.
It is one of the very few pearl gradings with an independent body behind it, which is what separates it from a seller's own AAA.
When you are buying
If you are buying a serious Akoya strand, hanadama is the one label that means something verifiable. The certificate should name the strand's length and pearl sizes so it cannot be moved to another necklace.
Akoya Pearl
The classic small round white saltwater pearl from Japan and China, usually 5mm to 9mm. The pearl in a traditional single-strand necklace.
Pearl Grading
The A to AAA scale used to rate a pearl on lustre, surface, shape, colour matching and nacre. There is no global standards body enforcing it.
Nacre
The material a pearl is made of: microscopic aragonite platelets glued in layers by conchiolin. Thickness determines both lustre and lifespan.
Certification Labs
Independent gemmological laboratories that identify and grade stones and pearls. The name on the report is what gives it weight.