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Pearl Grading Guide - Overview

Pearl Grading

PEARL GRADING – An Insider’s Guide to Grading Gorgeous Pearls


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 Grading Scale so you know exactly what to look for when purchasing 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.



Pearl Value Factors (there’s 7 of them!)

Value Factors 7 Pearl Attributes
Luster - this is the biggest value factor to pay attention to. 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.
Value factors pearl luster
Shape - 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.
Value factors pearl shape
Color - 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. To learn more visit our Pearl Colors Page.
Value factors pearl colors
Surface Blemishing - 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. However, because pearls are a product of nature, 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.
Value factors surface quality
Size - 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). To learn more about pearl sizes visit our Ultimate Guide to Pearl Sizes Page.
Value factors pearl size
Natural or Cultured - 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 have a premium price.
Value factors pearl farm kamoka
Matching - describes 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 strand. Matched pairs for 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.
Dark Man Rises Layout

What’s the Deal with Pearl Grading?

Grading Pearls After Harvest
Right now, there’s no set internationally agreed upon grading scale for pearls. That means that pearl grading is subjective, depending on the seller you’re dealing with.

My biggest concern regarding A-AAA vs A-AAAA or AAA+ or AAAAA grading scales is that instead of making pearl grading standards as easy as possible to understand, it actually creates a ton of confusion. So be careful! If you see a strange grade like AAAA+, then buyer beware.

Here’s how this works: Instead of having AAA representing the "best" pearl grade, the quadruple AAAA is used to represent AAA grade pearls, and the AAA actually represents the AA+ grade, with subsequent downgrades in pearl quality all the way down the line.

So you think you're buying AAA (aka the best quality) at a lesser price than you'd pay here, you're still only getting AA+ Quality pearls, and shelling out a premium for AAAA pearls that are the equivalent of our AAA. Often this inflation of the grading scale isn't properly described, and many customers new to pearls and unfamiliar with the intricacies of pearl grading end up disappointed.

Pro-Tip: Ask to see a detailed description with specific criteria for each pearl grade so you know exactly where you stand. It’s easier to compare apples to apples that way.

Explaining Pearl Grading Systems

PurePearls.com uses the A-AAA grading scale, and what I like so much about it is its 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 and Freshwater pearls, but also converts easily from the Tahitian and South Sea grading scales of A-D that most pearl farmers use. Pure converts all A-D Tahitian and South Sea pearl grades to the A-AAA scale to make things easier to understand and consistent across the board, and the grading charts shown below depict the A-AAA scale for your convenience.

Akoya and Freshwater Pearl Grading

A AAA Akoya Grading
Cultured Akoya and Freshwater pearls are graded 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.
A AAA Akoya FW Grading Overview
Click on image to zoom.
I don’t stock any inventory for either Akoya or Freshwater pearls graded under AA+ Quality due to customer satisfaction and quality control issues.

Tahitian/South Sea Pearl Grading

Tahitian pearl grading glamour
Tahitian and South Sea pearls are primarily graded according to Shape, Surface Quality and Luster. 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.
A-D Tah Grading Overview
Click on image to zoom.
Pro-Tip: Tahitian cultured pearls MUST have a minimum nacre depth of 0.8mm per side (so 0.16mm 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.

To maintain a high level of quality for all my customers, I only stock AAA Quality Tahitian and South Sea pearl pendants, earrings and rings. This means that all our Tahitian and South Sea pearl jewelry will set clean with the brightest luster and prettiest overtones.

So, what’s the deal with AA+/AAA type grades?

Pearl grade intermediate aa plus aaa tahitian necklace
With full strand pearl grading, there will be layouts that combine many AAA Quality and AA+ Quality, or AA+ and AA 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 AA+/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.

A Note About "Gem" Grade Pearls …

Hanadama-Akoya-Close-Up
It is true that with pearls and other precious colored gemstones that there will always be a better "best of the best" specimen than what fits in the A-AAA Scale … pearls that cannot be sold at a "lot price". This is not to be confused with ‘AAAA’ pearls! Gem Quality pearls are rare strands or 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.

I always keep a special eye out for rare and beautiful pearls on buying trips each year, and regularly send out special email updates for collectors about the newest treasures I come across. These items are not typically offered on the site as a standard item to be ordered due to rarity and pricing issues (and they move fast!). Feel free to contact me directly if you’re looking for one of a kind, rare items Ashley@purepearls.com or sign up for the Collector’s Email List.

Common Pearl Blemishes

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 – and pearls are just like that! Tahitian Baroque Inclusions Unlabeled 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. So in this section we’re going to learn 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. Tahitian Inclusion Samples Common pearl blemishes include:

  1. Dents/Divots: Medium to large indentations in the nacre. These can be deep or shallow, match the body color of the pearl, or be a brownish/greyish color.

  2. Score Marks: Scoring is usually light, pencil thin (or slimmer) lines in the nacre. The majority of the time, these marks are colorless and usually not noticeable.

  3. Bulleting/Mottling: A light plating pattern formed on the surface of the pearl while the pearl is formed inside its host oyster. Mottling is not considered an inclusion, as it is actually indicative of thick nacre layers and does not count against the pearls A-AAA grade.

  4. Knobs/Tips: These are a growth characteristics, and not necessarily determined to be inclusions. These extrusions form on the end of a baroque-shaped pearl, and can be long or short, bubble-like or pointed. These knobs and tips do not usually affect the durability of the pearl as long as they are not chipped. These features can add touches of unique, artistic flair to a baroque strand of pearls.

  5. Pin pricks: Very small indentations in the nacre. These can be small, individual marks, or grouped together to create a larger area of surface blemishing. Pin prick inclusions do not affect the long-term durability of the pearl, and are colorless or match the pearl’s body color.

  6. Circles: Circling is also another growth characteristic of baroque pearls, with concentric rings running around the circumference of the pearls. They can be very subtle, or grouped together heavily, and impart a one-of-a-kind artistic look to the pearls.

Other pearl inclusions include: wrinkles, blinking, chalky spots, flat spots, ridges and pitting. Ready to get more in depth about pearl grading by type? Click the links below to head directly to each pearl type:
Akoya Pearls Grading Tahitian Grading
Freshwater Grading South Sea Grading

About the Author

Ashley McNamara Pure Pearls CEO I’ve been with Pure for well over 10 years and am incredibly passionate about what I do! My 15 year career in the jewelry industry spans working in the precious colored gemstone wholesale sector, as well as stints in diamond bridal jewelry manufacturing division. I earned my GIA Pearls certificate in 2004.

I’ve written extensively about pearls for many online trade publications including Jewellery Net Asia, the CPAA (Cultured Pearl Association of America), and of course, Pearl-Guide.com on all things pearl-related.

Feel free to email me with any questions or issues – I am always happy to help!
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