How to Grade South Sea Pearls
South Sea Pearls have the same grading system as Freshwater pearls which is as follows:
Nacre is between 2.0-4.0mm thick
The luster is considered sharp with a good rate of reflection
Reflected light sources have mostly crisp edges with slight blurring
Less than 10% on each pearl surface has some blemishes
Near-perfect matching is possible with little to no variation in color, tone, luster, shape or size
Nacre is between 2.0-4.0mm thick.
There is a fair amount of reflection with a mostly sharp luster
Reflected light sources have blurred edges
Less than 20% of the pearls surface may have slight blemishes
On an 18-inch strand, only 1-2 heavy blemishes are allowed
Very good matching; little variation in shape color, tone, luster, or size
Nacre measures between 2.0-4.0mm thick.
Pearls have a poor rate of reflection with a luster that is good to soft
Reflected light sources contain blurred edges
Less than 30% on each pearl surface show blemishes
One to two heavy blemishes are allowable on an 18-inch strand of Mabe pearls
Very good matching with little variation in color, luster, tone, size or shape
Low rate of reflection with a luster that is considered fair to soft
Reflected light sources are usually quite blurry
Less than 40% of the pearl’s surface is blemished
Deep inclusions should not make up more than 10-15% of the pearl’s surfaces with heavy blemishes visible
Fair to good matching with some variation in color, tone, luster, shape or size.