Pearl grading: Approximate method but proven consistency

Pearls are a classy set of organic gemstones extracted from the bottom of the ocean. Bright and shiny nacre pearls have always been an item of fascination for women. Much before diamonds became a woman’s “Best friend for life”... the tag definitely belonged to the pearls. If you are looking for a lustrous set of pearls in the market, you should know how they are certified for authenticity and clarity.

Why are pearls graded?

Like all high priced items, pearls too have to fulfil the regulated set of characters and factors to make it into the real gemstone market. Certified graded pearls earn higher prices compared to those that have no backing from any certifying agency. Even from gifting point of view, a certified pearl is what most individuals prefer. Ungraded pearls run the risk of losing their dyes, lustre and sheen within a year’s time! And you don’t want to be tagged as a lousy pearl shopper for that reason.

Grading of pearls: The methodology:

Pearls are graded according to the contemporary best practices in the gemstone industry. Agencies like Swiss Gemological Institute (SGI), Gemological Institute of America (GIA) and Pearl Science Laboratory of Japan are forerunners in the study of organic pearls and designating them as commercially viable items.

One key thing to know in pearl grading is the fact that there is no universal grading system for them. There are two major grading scales used in the pearl industry.

-  American scale: AAA-A
-  Tahitian system: A-D scale

American scale of pearl grading:

Mostly applied to the Akoya pearls, the AAA grading marks the purest and the most physically perfect sets ever manufactured. According to this scale, the highest quality of any pearl is tagged as ‘Hanadama’.

Pearls with a thickness of 0.4 mm with a diameter of 0.8 mm are considered the purest and most perfectly formed material. And that is the benchmark reference for a Hanadama pearl.

AAA pearls: Pearls with 95% surface lustre intensity, with a nacre thickness of at least 0.4 mm.

AA pearl: Surface lustre between 75% and 90%, there is a visible spotting. The nacre thickness can be between 0.375 and 0.400 mm.

A pearl: Usually unpolished and undyed pearls are placed in this scale, where the surface lustre is less than 45%. Defects are evident and have nacre thickness of 0.25-0.30 mm. Still used for jewellery, but of cheaper quality.

Tahitian scale:

Polynesian pearls are graded based on the lustre intensity of the surface and the uniformity of shade.

A: Best pearl quality with least imperfection and highest lustre intensity
B: Pearl quality with 70% lustre consistency and no defects visible to eyes
C: Pearl lustre intensity at 60% but with significant spotting and minor colour inconsistency
D: Least lustre intensity below 50% with no major defects

According to the Tahitian scale, a pearl with a nacre thickness of less than 0.8 mm is not considered for sale in commercial market.
Both scales are accepted, as they more or less assure the pearl durability and consistency when used for commercial purposes.