Wanna know a secret?

Pearl grading standards are a MESS.

Seriously – standards are all over the place, they vary from seller to seller, farmer to farmer and auction to auction. Walking an industry show and talking to pearl farmers entails learning as many as 30 new grading scales in day in order to navigate the pearls on offer.

What I take with me when I go is my special grading hank that features pearls with all my grading benchmarks so I can compare pearls to make sense of it all while I’m there.

Now, obviously you don’t have that option.

BUT, what I can do is create simple breakdown of each grade’s specific standards using the A-AAA and A-AAAA Grading Scales so you know exactly what to look for when purchasing a pearl necklace or earrings, bracelet, pendant, etc.

GIA tells us to use the 7 Pearl Value Factors in combinations to properly evaluate and assign pearl value to all pearls, whether cultured or natural. That said, GIA pearl grading is unique to GIA, and they do not use A-AAA or A-AAAA grading systems to evaluate pearls.

Follow the links below to jump straight to the specific pearl grading guide you’re looking for, or read on a bit more for an overview of the popular Grading Scales in use today, and how they relate to your pearls.

Luster measures the rate of reflection (how crisp and detailed it is) on a pearl’s surface, and the amount of light reflected on the pearls.

Beautiful luster makes or breaks pearls as a gemstone - pearls without great luster can end up looking like chalky beads. Basically, the brighter, sharper and more reflective a pearl is, the more valuable it will be.

Read More: What Causes Luster in a Pearl

The rule regarding pearl shapes is:  generally the more perfectly round in shape a pearl is, the more rare and prized it is. However many pearl connoisseurs enjoy the unique distinctiveness of baroque pearls.

Baroques are off-round, drop and asymmetrical in shape, and are graded according to symmetry.

Read More:  Guide to Pearl Shapes

While many prefer the classic white pearl, pearls come in every color of the rainbow.

Naturally colored pearls like black Tahitian pearls or Golden South Sea pearls are graded on their color’s depth and saturation - the more strongly colored pearls will be more rare and valuable. Certain overtones or exotic body colors command premium pricing at auctions.

Read More:  Ultimate Guide to Pearl Colors

Pearls that feature clean surfaces without inclusions like pin-pricks, scoring marks, chalky spots and wrinkles will be much more highly valued than pearls with multiple blemishes.

Because pearls are a product of nature however, there will always be some form of blemish - even if you can’t view them with the naked eye. This is why we will never call our pearls flawless.

It's just true that large pearls are rare in nature. The majority of cultured pearls harvests consist of pearls under 10.0mm and wild pearls in very large sizes are the rarest of the rare, so the bigger they are the more valuable they are (all other value factors being equal).

Read More: Ultimate Guide to Pearl Sizes 

95% of all pearls on the market today are cultured pearls, meaning that humans played a role in pearl formation. Natural, wild pearls from the ocean are very rare and command a premium price, especially well-matched strands, earrings and natural pearls with coveted provenance or special story behind them.

Matchingdescribes how well pearls are matched within a pair, or an entire layout.

For Akoya pearls, matching must be near-perfect with little to no variation from pearl to pearl throughout the entire Akoya strand. Matched pairs for Akoya earrings must feature less than 0.15mm difference – the match must be as close to exact as humanly possible.

For South Sea and Tahitian matched pairs for earrings, a difference of up to 0.50mm is allowable between pearls. Tahitian and South Sea pearl necklaces will often feature graduated layouts (meaning pearls can range in size by a few millimeters), and multi-colored layouts are common.

There is no single, worldwide standard for pearl grading. Each jeweler uses their own scale, which means the grades are only meaningful within that particular store or brand.

Some use an A–AAA or A–AAAA system, while others use AAAAA or 6A scales. The important thing to remember is that the top grade -whether that’s AAA, AAAA, or even AAAAA - simply represents the highest quality pearls that specific seller offers. It does not mean you can compare those grades across different stores. For example, one brand’s “AAAAA” pearls might be the same quality as another brand’s “AAA” pearls.

This is why pearl grading can feel confusing and sometimes misleading. To shop smart, always look for a clear description of what the grades actually mean—details about luster, surface quality, shape, and size. That way, you know exactly what you’re getting and can compare more fairly between different jewelers.

PurePearls.com uses both the A-AAA and A-AAAA grading scales, and what I like so much about them both are their simplicity. Grades are based upon a certain percentage of surface blemishes allowable, specific rate of luster (the sharpness of reflections) and shape.

The A-AAA scale is used most commonly with Akoya pearls. It is known overseas as the Japanese Grading System.

Our Freshwater, Tahitian and South Sea grading scales of A-AAAA are converted from the 4-tier systems that most pearl farmers use. Pure converts all A-D Tahitian and South Sea pearl grades to the A-AAAA scale to make things easier to understand and consistent across the board. The pearl quality guide charts we have listed below will help you determine which pearl makes the grade.

Cultured Akoya pearls are graded using the Japanese Pearl Grading System, using the A-AAA Scale with the addition of Hanadama Akoya pearls representing the highest pinnacle of the pearl type.

The A-AAA system evaluates pearls according to surface quality, luster, and perfection of shape (roundness and symmetry). Akoya pearls are also graded on nacre thickness, which is a visual inspection completed by the grader rather than via x-ray analysis. The only exception to this is for Hanadama pearls which are x-rayed at the Pearl Science Laboratory in Tokyo. The pearl quality chart below shows you what benchmarks to look for.  

Cultured Freshwater pearls are graded using a version of the Chinese Pearl Grading System which separates pearls into Class I, Class II, Class III and Class IV grades according to surface quality, luster, matching and perfection of shape (roundness and symmetry).

In order to simplify this classification system and maintain consistency with other popular grading systems, many vendors convert this Class system to a whole letter A-AAAA Scale. Class I pearls would be the highest grade, with Class IV representing the lowest pearl grades. Much of the Chinese Grading System utilizes the Japanese A-AAA Grading System to evaluate pearls (luster and surface quality mainly), and ditches the "+" signs, relying on whole-letter grades instead.  

See the chart below for a detailed breakdown of the A-AAAA system and the statistical benchmarks pearls need to meet in order to make the grade.

Black Tahitian pearls are primarily gradedwith the Tahitian Pearl Farmer's A-D Grading System, which takes factors like shape, surface quality, luster and color as the primary focus. This system easily converts to the A-AAAA system widely employed in the United States.  

Variations in pearl body color, overtones and color saturation levels (with as many as 80 “official” variations!) mean that the value factors for color need to be evaluated individually.

Pro-Tip:  Tahitian cultured pearls MUST have a minimum nacre depth of 0.8mm per side (so 1.6mm total) in order to qualify for export. Harvests are examined and certified at random by the Perliculture Department of the Pearl Ministry for nacre thickness. Average nacre thickness for Tahitian pearls remains at 1.0mm depth or more.

With full strand pearl grading, there will be layouts that combine many AAA Quality and AA Quality, or AAA and AAAA Quality pearls. This is done to maintain a consistent “tone” throughout the necklace in terms of matching for size, overtone or luster, and also to ensure price points remain reasonable.

These strands would be graded as AA/AAA or A/AA or AA/A and so on. Essentially, what this means is that a layout could have a AA Quality rate for surface blemishing, but fantastic AAA Quality luster (or vice-versa, with very clean pearls and medium-grade luster), and so receive a AA/AAA Quality grade.

Gem quality pearls are very rare strands or single pearls come along once in a while with unparalleled luster, nacre thickness, crystalline transparency, orient, etc., and simply must stand on their own and be priced out individually based upon what the market will bear.

The inclusions in an Emerald are known in French as “les jardins”, or “the gardens”, and each one is totally unique – a built-in identification system of sorts actually – pearls are just like an Emerald in that respect.

Pearls are what’s known as  ‘organic gemstones’. They are the creations from a biological process (the others being coral, amber, jet and ivory), and as such will feature growth characteristics … kind of like Mother Nature’s fingerprints on her creations.

In this section we’re going to learn how to tell what a blemish is, and what it is not. The slightly circled Tahitians pictured above are a perfect example to work with as they feature a good variety of common inclusions, as well as typical growth features that aren’t considered inclusions at all.