Akoya Pearls: A–AAA Grades, PSL Certification & Natural Blue

Akoya are the classic round, mirror-bright pearls most people picture when they think of a pearl strand. This guide covers how everyday, uncertified Akoya are graded, what lab certification adds, and the rare natural blue Akoya.

What are Akoya pearls?

Akoya were the first bead-nucleated cultured pearls. A shell bead is placed in the oyster, which coats it in nacre over a growing season or two. Because the Akoya oyster is small, the pearls are too: most run 6–8 mm, and anything above 10 mm is rare. Akoya are usually very round, with a sharp, mirror-like luster and white bodies carrying rosé, silver or cream overtones.

Akoya nacre is thin compared with South Sea or beaded freshwater pearls, often a fraction of a millimeter. That’s why nacre thickness matters more in Akoya grading than in any other type, and why luster and surface do so much of the work.

Uncertified Akoya: what A, AA and AAA mean

Most Akoya sold is not lab-certified. Dealers grade it themselves, usually on an A to AAA scale, sometimes with steps in between such as AA+ or AAA+, or house names like “Gem.”

As a rough guide, this is how the letters are commonly used:

Grade	Typically means
A	Softer luster, visible blemishes and more off-round pearls. An entry grade.
AA	Good luster with some blemishes; mostly round. A common mid-range grade.
AAA	High luster, clean surfaces, round and closely matched. A seller’s top grade.
AAA+ / Gem	Some sellers add a step above AAA for their very best strands.

What makes a fine Akoya

Factor	What to look for
Luster	The most important factor: sharp, bright reflections you can see your face in
Surface	Fewer and smaller blemishes; under a strand’s own weight, look where pearls touch
Shape	Round is the standard for Akoya; off-round pearls are priced lower
Nacre	Thicker nacre lasts longer and glows more; thin nacre can look chalky or show the bead
Color and overtone	White with rosé overtone is the classic; silver and cream are also common
Matching	Pearls in a strand should agree in size, color, luster and shape
Size	Value climbs steeply above 8 mm, and above 10 mm is rare

In the press: GIA featured our 11–12 mm Japanese Akoya strands, which took more than one harvest to match.

PSL certified Akoya

Pearl Science Laboratory (PSL) issues the trade’s most widely recognized standardized grading for Akoya. Its certified tiers for white Akoya, from entry level to the top, are Rose, Premium Rose, Hanadama and Tennyo. Each comes with a numbered report, so the grade is tied to a specific strand rather than a seller’s say-so.

Natural blue Akoya pearls

Natural blue Akoya are among the rarest Akoya of all. They are not a separate variety or a treatment: they come out of the same oysters, in the same harvests, as white Akoya.

How natural blue Akoya form

The blue comes from dark organic material, mostly conchiolin (the protein that binds nacre together), deposited between the bead and the nacre or within the inner nacre layers. Seen through the translucent nacre on top, that dark layer reads as silver-blue to blue-gray. Nothing in farming can reliably produce it, so it turns up in only a small share of each harvest, and the colors and tones vary from pearl to pearl.

That makes matching a full strand slow: blues have to be collected and sorted across harvests to line up color, tone and luster.

Madama and Blue Rosé: PSL’s natural blue designations

For natural blue Akoya, PSL adds a special designation to its report, much as Hanadama and Tennyo do for white Akoya. Two of these are Aurora Madama and Aurora Blue Rosé, and Madama ranks higher. PSL places a Madama strand in its highest-quality category, and a Blue Rosé strand in its strongest-luster (teri) category. Both reports confirm the blue comes from organic material in the pearl, the finding that marks a natural blue.

Here is what the two reports record. Read it alongside the note above: the lines below don’t capture matching across the strand, which is where Madama pulls ahead.

Report line	Aurora Madama	Aurora Blue Rosé
Rank	Higher	Below Madama
Designation	Highest-quality category	Strongest-luster category
Size	9.0–10.0 mm	8.0–8.5 mm
Luster (teri)	Very strong	Very strong
Interference color	Vivid, confirmed	Vivid, confirmed
Nacre thickness	0.9 mm	0.5 mm
Body color	Blue	Blue
Blemishes	Very slight	Slight
Shape	Round	Round to symmetrical
Color origin	Organic material (“natural blue”)	Organic material (“natural blue”)

Frequently asked questions

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