Can pearls be graded, just like diamonds? Absolutely! Here’s how pearls are graded. There are two main systems used to grade pearls: the Polynesian ‘Tahitian’ system and the ‘AAA – A’ system. The former is used to grade Black Tahiti and other Saltwater pearls; the latter is used to grade cultured freshwater pearls.
How pearls are graded under the Tahitian System
Under the Tahitian System, saltwater pearls are graded on a scale of ‘A’ to ‘D’, with grade A representing pearls of the highest quality.
Grade A pearls have a brilliant luster and a clear, reflective surface with at most 10% blemishes or flaws. These pearls are round, often with deep overtones of pink, peacock blue or gold. They have a thick nacre coating which contributes to the luster of the pearl. They have also large pearls, with a mm width of more than 14 mm.
Grade B pearls have a good luster, with at most 33% blemishes or flaws. These flaws are often unnoticed from a distance, and can only be seen upon close examination. These pearls are round or semi-round, and have mm widths between 12 to 14 mm.
Grade C pearls are still lustrous, with at most 60% blemishes or flaws. These pearls are usually semi-round, and vary more than 5% in diameter. They are smaller than Grade C pearls, and have less pronounced color overtones.
Grade D pearls have visibly obvious flaws such as deep dents or cracks, and are irregular in shape.
How pearls are graded under the AAA – A system
The ‘AAA – A’ system is usually used to grade freshwater pearls. The ‘AAA’ grade is the highest possible grade (though some jewelers may quote the nonstandard ‘AAAA’ grade).
‘AAA’ pearls have a strong luster, minimum blemishes and flaws, and are rounder than pearls of other grades. Nonetheless, do note that freshwater pearls are rarely perfect spheres. These pearls are large, with mm widths more than 8 mm.
‘AA’ pearls have a good luster and may have a flawed surface – though this can be disguised by drilling the flawed area. These pearls are less round than ‘AAA’ pearls, and usually have overtones of white, pink, silver or green. They have a thinner nacre coating, and are of mm widths between 5 mm and 8 mm.
‘A’ pearls have much less luster, but still look elegant due to their natural shapes. They have more than 25% blemishes and flaws, but these cannot be seen from a distance. With a thinner nacre coating, and mm widths between 1 mm and 4 mm, they are smaller than the higher grade pearls. But they come in a lovely variety of shapes – oval, pear, button, baroque, rice, seed pearls – and thus cater well to different tastes.
The AAA – A system is slightly more flexible than the Tahitian system, for sellers can give middle grades such as AA+ for pearls with properties that cross two specifications.
Regardless of grade, a thick nacre coating is always desirable, for it protects the pearl in many ways (discoloration, cracking, age, etc).