Hanadama is a Japanese term that was coined by the founder of the cultured Akoya pearling industry, Kokichi Mikimoto, which means spherical flower. Hanadama pearls would comprise about the top .01% of the best quality AAA pearls ever harvested. The Hanadama grade is still used to this day to designate the best quality Akoya saltwater pearls that can be found anywhere in the world.

In order to have a hank of pearls certified as being Hanadama they are submitted to the Pearl Science Laboratory in Japan to under go a series of tests on random pearls from the strand; such as soft x-rays, light spectro photometric reflectance, magnification and inner inspection by optical fiber. This allows the PSL to exactly measure nacre thickless, luster, surface imperfections, (etc.). At the end of this analysis if a hank has met the criteria for being of Hanadama grade a numbered certificate will be assigned to the hank of pearls by the PSL deeming it to be Hanadama grade.

The PSL is the premiere authority in the world which can assign a Hanadama grade. A strand of pearls cannot be referred to as Hanadama unless it is accompanied by the PSL certificate.

The grading is not subjective, and must meet the following criteria:

Nacre depth must not show to be less than 0.4mm (0.8mm when two sides are added)
Teri-value (luster) analysis must be very strong
Surface imperfection (inclusion) grade must read very slight

Although the certificate allows for thicker nacre grading than the minimum required of 0.4mm, it is important to remember that this test is performed on a random selection of pearls. Each pearl will vary on every Hanadama strand and will have pearls with nacre depths ranging from 0.4mm to 1.0mm or higher. It is impossible to guarantee consistent nacre depth within a single strand. Every pearl is unique - and that is the beauty of how Mother Nature creates pearls.

The PSL certificate does not allow for grading of no imperfections. This is because all pearls will have some degree of imperfection. Pearls are an organic gem, and though imperfections may be indistinguishable to the eye, they will still exist. For that reason the Pearl Science Laboratory of Japan does not allow for a 'perfectly flawless' grading.