Tahitian Pearl Grading
This guide has adopted the Tahitian pearl grading standards set forth by GIE Perles de Tahiti, and the Ministere de la Perliculture of Tahiti; the governmental organizations of French Polynesia dedicated to the promotion and regulation of Tahitian pearls, and consumer protection.
Please note, we do not subscribe to superfluous grades such as AAA+ and AAAA. These are not industry-accepted grades.
Guide to Grading Tahitian Pearls
Tahitian pearls are all about COLOUR. Unique, distinctive and saturated colours. Cherries, Aubergines, shimmering Silvers and Aquamarines, delectable natural Chocolates – and the list goes on.
These colours are called “overtones” and are a secondary colour that lies shimmering over the main, primary body-colour of the pearl. In the case of Tahitians, these overtones lend a colourful brilliance to their dove grey to dark charcoal grey body colours, and make them a distinctive and highly coveted gem for pearl appreciators around the world.
Second to the great colour is LUSTRE. Cultured Tahitian pearls traditionally have slightly softer lustre than other cultivated types.
That said, Tahitian pearls can and do display metallic-levels of lustre with highly detailed reflections and very sharp, crisp squares of reflected light in their surfaces.
Cultured Tahitian pearls that do not fall into any category, or do not meet the minimum nacre depth requirements of 0.8 mm per radius, do not pass the mandatory examination of the Ministere de la Perliculture of Tahiti. Those pearls are refused for export and destroyed.
The Science behind Pearl Colour and Lustre
As with all other cultured pearl types, the visual phenomenon of Body Colour, Overtone and Lustre are due to the compaction and smoothness of their crystalline nacre layers. Tahitian pearls are bead-nucleated, meaning that a mother of pearl round bead nucleus is inserted into the gonad of the host oyster, which then begins covering the bead with concentric layers of nacre to eventually form a pearl.
Nacre is made up of crystalline calcium (CaCo3) which the oyster secretes to smooth over the bead nuclei irritating the soft inner body of the mollusc, eventually creating a pearl.
CaCo3 is composed of transparent to semi-transparent aragonite platelets and conchiolin which is the organic glue interspersed between the layers to hold it all together. (Think of conchiolin like the layers of concrete between bricks in a wall).
Tahitian pearl conchiolin takes on very dark pigments such as reddish-brown, brown, grey and black. This contributes to the pearl’s trademark dove grey to dark charcoal grey primary colours. (With white pearls, conchiolin is usually colourless or beige in colour).
The oysters are left in the water to continue their work for between 2-3 years, resulting in very thick nacre layers that both reflect and refract light striking and penetrating the various layers.
The tighter and more compact these layers are, the more intense the lustre and the deeper the colour.
Younger oysters have a faster metabolic rate, which contributes to an accelerated crystalline layering process and tighter nacre formation. Younger oysters are most often used to produce first-generation Tahitian pearls, ranging in size from 8-9mm up through 12mm.
Older oysters that survive their first (and second!) harvests are used to cultivate larger pearls because they’re large enough to handle the increased size of the bead nuclei. However as the older animals metabolism slows, so too does the rate of nacre layering, and the relative tightness of those crystalline platelets. This generally results in larger pearls of 12mm and up displaying more Steel and Silver overtones, and the trademark “satiny” lustre that Tahitians are known for.
Thus finding Tahitian pearls in large sizes with intense body colour and overtone saturations as well as amazingly reflective lustre and clean surfaces are rare in each harvest, resulting in premium prices.
Tahitian pearl oysters that survive 3rd generation pearl harvests are usually released to the wild to live out the rest of their lives in the open ocean, contributing genetic information to other wild oysters to strengthen populations.
Having mentioned the background science behind why and how pearls are beautiful, let’s move on to exploring the Tahitian pearl A-AAA grading scales, and the specific benchmarks that a pearl needs to meet in order to “make the grade”. Bear in mind that pearls are “organic gemstones”, meaning that they are the end result of a biological process. As such, cultured pearls will never be as flawlessly perfect as a synthetic glass or plastic bead can be – Mother Nature always signs her creations!
AA+ vs. AAA Quality Tahitian Pearls
Selecting a Tahitian pearl on the A-AAA spectrum allows you to consider the Pearl Value Factors most important to you.
Great colour saturation, or incredibly high lustre may trump eye-clean surfaces (and indeed may even “hide” surface characteristics) or perfectly smooth shapes.
Intermediate Tahitian Pearl Grading; often you’ll see Tahitian pearls that straddle the grading benchmarks, listed with AA+/AAA Quality or AA/AA+ Quality grades. These “intermediate” grades are assigned to pearls when the pearls almost-but-not-quite make it to a full grade, like AAA Quality.
Essentially what these intermediate grades mean is that the surface quality (i.e. amount of blemishing) is at a lower grade level, and the lustre and colour of the pearls pushes the pearls to almost a higher grade.
The reverse can also be true, but generally with very clean strands and softer lustre, we almost always assign it a lower grade anyways! Because what makes a pearl beautiful as a gemstone? That’s right: gorgeous LUSTRE and COLOUR.
Common Tahitian Pearl Blemishes
Inclusions are the science-y sounding jewellery industry term for blemishes or other growth characteristics that mar the surface of the pearl. In this section, we’ll break down what is and is not an inclusion (it’s not always what you might think): how these growth characteristics effect the pearl, and how they can affect value.
Growth characteristics and surface inclusions that are typical of the Tahitian pearl type are a practical and easy way to:
- Verify that the pearls are genuine cultured pearls and not man-made synthetics, 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 the pearl as yours and yours alone.
The vast majority of Tahitian pearl inclusions are grey or colourless in appearance, meaning that they are not easily noticed by a casual observer unless they are very deep, or very numerous.
Mottling/Bulleting of the Surface – this texturing of the surface resembles the marks of a tiny hammer on the pearl’s surface, and is indicative of very thick nacre. Mottling is not technically considered an inclusion, and does not count against a pearl’s surface grade.
Pin Pricks – These are small to tiny indents on the pearl’s surface. It looks as though the pearl had been pricked with a needle point. They can stand alone (which is preferable), or be clustreed together in groups which tends to give the pearl’s surface a “chewed” appearance.
Pits – These formations are pin pricks taken to extremes, and resemble large indentations, craters or even holes in the nacre. Pits count as heavy or deep blemishes when grading a pearl, and their best case scenario is that they are at least the colour of the pearl, and totally covered by nacre. Worst case scenario is they are very deep and display the organic conchiolin layer; jagged, sharp edges may eventually lead to chipping.
Score Marks / Grooves - This inclusion is maybe the most common one we’ve noticed on Tahitian pearls. You’ll notice these little marks on baroque and round pearls alike. Score marks look like someone has taken a pencil and drawn a shallow to deep channel through the nacre in a straight line. For the more shallow marks, the ends can appear to trail off lightly and disappear, giving the impression that the pearl has a small comet or shooting star on its surface.
Knobs – these form off the end of the main body of the pearl, and resemble small bubbles. Interesting features that add personality to a baroque pearl, these growth characteristics are also not counted as inclusions or blemishes. If they are chipped or cracked however, a knob may affect the pearls’ long-term durability.
Tips – Very similar to knobs, and also not considered an inclusion or blemish but are a growth characteristic. Tips are only seen on baroque pearl shapes, and can be rounded or elongated, pointy protrusions located at either end of a pearl. Tips do not affect the long-term durability of a pearl unless they are chipped or cracked.
Circles / Circling – Marketed as “Circles of Love” in the 1980’s, circles are a natural pearl formation. Easily recognized by concentric rings around the circumference of the pearl, these rings can be singular or grouped heavily together, giving the pearls a very unique look. Circles are NOT an inclusion, but inclusions can form inside them (usually pin pricks or scoring marks), they can even result in higher, more concentrated rates of colour.
Uneven Nacre Accumulation – When nacre building works perfectly inside the oyster, the crystal is laid down concentric layers over the mother of pearl bead nucleus creating a smooth surface. When nacre deposition is disturbed for some reason or other, a build-up of crystalline material can occur on the surface resulting in bumpy or uneven surfaces.
In Conclusion …
By far, the majority of Tahitian pearl blemishes will be small and match the pearl’s natural charcoal grey body colour and/or are colourless, blending with the surface and making them fairly unnoticeable to the casual observer. This is especially true if the pearl’s overtones and lustre are at high levels, masking marks and distracting the eye.
Inclusions are generally considered to be “undesirable” by general consensus, but when looked at through the lens of a pearl appreciator, they become part of the unique character of your pearl. Like a fingerprint, or a gorgeous “jardin” or “garden” which is what the French name the inclusions in an Emerald, a pearl’s inclusions mark your gem as an individual creation of Mother Nature herself.