Akoya Pearl Grading
This short guide is a handy reference for learning about Akoya pearls and the A-AAA Grading Scale.
Please note, we do not subscribe to superfluous grades such as AAA+ and AAAA. These are not industry-accepted grades.
Guide to Grading Akoya Pearls
A smooth, unblemished surface, shimmering iridescent flashes of pink, blue, green and (in the best cases) violet, shimmering over a white primary body colour, and of course, their trademark “ball bearing” or mirror-like lustre. These are all the hallmarks of beauty that an Akoya pearl can possess.
A cultured saltwater Akoya pearl is the product of a synthesis between humans and nature. A mother of pearl shell bead nucleus is inserted into the host oyster, along with a square of donor mantle tissue from another oyster who has previously borne pearls of high or exceptional value, and the oyster is left to begin secreting around the nucleus, forming a pearl.
The crystalline nacre layers are made up of microscopic aragonite platelets composed of calcium carbonate, and bound together with an organic “glue” of sorts called conchiolin. The aragonite platelets are fairly transparent to slightly tinged in colour, able to both reflect and refract light rays striking their surfaces, giving pearls their trademark lustre and subtle glow. The tighter and more compact this arrangement of crystal is, the brighter the lustre the pearl displays and the greater the amount of orient or iridescence.
This internal structure is what gives pearls their beauty, and makes them worthy of their designation as a precious gemstone. However, because these gems are the result of a biological process, they will never be totally, completely, flawlessly perfect. Mother Nature always leaves her mark!
After this bit of science behind why and how a pearl is beautiful, we can move on to learning about each pearl grade, and what it takes for pearls to qualify.
Akoya Pearl Grade Comparisons
Both the AA+ and AAA Quality Akoya pearl grades are pretty close in appearance to the casual observer i.e. someone who’s about 30-cm or more away from you looking at your pearl shouldn’t be able to tell which is which.
Both qualities are near to perfectly round in shape, their surface inclusions are largely white or colourless, making them not easily visible unless you’re conducting an up-close and personal inspection. The primary difference between the AA+ Quality and the AAA Quality Akoya pearl is one of lustre. The lustre on AAA Quality Akoya pearls will be sharper, brighter and have a greater visual ‘depth’ than that of the AA+ grade pearls.
Common Akoya Pearl Blemishes
As mentioned earlier, Mother Nature always leaves a mark on her creations. There are a number of common growth characteristics and surface inclusions you can regularly spot on almost any pearl that are typical for the Akoya type. These markings are a practical and easy way to:
- Verify that the pearls are genuine cultured pearls and not man-made imitations, which feature perfect, identical beads throughout an entire layout.
- Identify that particular set of cultured pearls as yours. As you become familiar with the character of your pearls, you’ll notice that each pearl’s inclusions act as a built-in identification system, marking every pearl as yours and yours alone.
The vast majority of Akoya pearl inclusions are white or colourless in appearance, meaning that they are not easily noticed by a casual observer.
Additionally, most Akoya pearl blemishes are fairly small and shallow, covering less than 10-15% of the total surface area of the pearl and so are very unlikely to affect the long-term durability of the gem.
- Mottling/Bulleting – this is a faint plating pattern on the pearl’s surface, and considered to be the result of very thick nacre accumulation. As such, this is not considered an inclusion per se. A colourless feature, this type of growth characteristic does not impact the beauty of the necklace if occasionally found upon up-close inspection, and certainly does not affect the long-term durability of the pearl.
- Uneven Accumulation of Nacre – in a perfect world, crystalline nacre is deposited in evenly concentric layers over the bead nucleus during pearl formation. The layering process has then been interrupted/disturbed in some way, causing a build-up of nacre in a single area.
- Clustered Pin Pricks – tiny pin point indentations in the nacre, clustered together in small groups. If clusters are too numerous, the pearls can have a “chewed” appearance.
- Blinking – this occurs when the nacre covering the shell bead nucleus is very thin. You can observe “blinking” when examining the pearls up close (at a distance of 15-cm or less) by slowly rotating sections of the strand in front of a strong light source. The internal bead will appear to “flash” a yellow-orange colour at you.
- Single Pin Pricks – tiny pin point indentations in the nacre, isolated from any others. Tiny, and covered in the same colour as the rest of the pearl’s nacre, pin pricks are often only distinguished upon up-close, careful inspection and do not impact the pearl’s durability or beauty.
- Scaly Spot – this is a clear, colourless inclusion called “uroko” in Japan; it usually indicates some kind of event or growth disturbance while the pearl was being formed inside the oyster.
- Diffused Lustre – this will show up wherever you see light reflecting off the surface of the pearls … this is not a pearl blemish, but it is one of the 7 major value factors of pearl grading, and as such merits inclusion here while it’s an easily showcased feature. Notice how the edges of the reflected light sources begin to soften and break up, giving the pearl’s lustre a softer, less defined look.