Classification of cultured pearls

The value of a cultured pearl is determined by multiple criteria, such as the orient, color, nuance, size, shape and quality.
In this article, we will explore some of these criteria.

Color

Freshwater cultured pearls are often white, with naturally occuring cream, pink, and mauve nuances. Freshwater pearls in blue and chocolate colors are artificially tinted, and have to be labelled as such.

                                                                    
                                                                    White freshwater cultured pearls

Tahitian cultured pearls have a vast amount of colors and nuances. Most pearls have a grey base, more or less dark, and have a nuance that can be of almost any color. From green to blue, and even aubergine. The most prized and expensive colors and nuances are aubergine, peacock and blue.
                                                                   

                                                               Dark grey Tahitian cultured pearl with a green nuance

Australian cultured pearls have colors and nuances ranging from silver-white all the way to golden, emcompassing the ravishing Champagne color.
Also known as South sea pearls, and golden cultured pearl, these pearls are cultivated in countries in Oceania and all the way to Indonesia. Each region having slightly different colors than their neighbors. Australian pearls having generally lighter colors, and Indonesian pearls often veering towards orange nuances.

                                                                  

                                                               Gold nuanced Australian cultured pearl

Akoya Japanese cultured pearls are generally white with a superb shine and superior orient, compared to freshwater pearls. They can take cream and ivory nuances, and some are artificially tinted black and even gold.
                                                                 

                                                                 Akoya Japanese cultured pearls with a cream nuance

Size of cultured pearls

The size of cultured pearls depends on the type of pearl. They can be anywhere from 2mm to 20mm in diameter. There can exist naturally occuring pearls (cultivated or not) that are smaller than 2mm, or bigger than 20mm, but those are extremely rare.

Here is a brief look at the average range of sizes per types of pearl available on Poemana's store.

Tahitian pearls and Australian pearls (the latter also called South sea pearls) are between 8mm and 20mm. They are rarely smaller, and only with extraordinary odds are they bigger. The average cultured pearl is between 9 and 10mm. At these sizes, the pearls are big enough to be appreciated, without being overwhelmingly large.

Freshwater pearls are between 2mm and 10.5-11mm. They are rarely found above that size, and pearls between 2 and 4mm are so small that they are rarely commercialized, let alone used.

Japanese Akoya cultured pearls are generally between 5 and 10mm. Their size is very homogenic, and jewellers tend to use pearls between 6 and 7.5mm.

Shape

Cultured pearls can be: round, semi-round, button shaped, drop shaped, pear shaped, oval, baroque, and in the case of Tahitian pearls, circled. Tahitian pearls are also found as what is called a Keshi, very irregularly shaped devoid of a nucleus. These pearls are only used by certain jewellers who want to make particularily unique jewelry.

Surface quality

There are two systems of classification adapted to cultured pearls.
The GIA system, created by the Gemological Institute of America, an international reference which we, Poemana, use to describe and grade our pearls.

The Service de Perliculture de Polynésie (SPP, or pearl cultivating service of Polynesia in English), used notably for Tahitian pearls.

Both systems are valid, and can be used almost interchangably.

Here are the possible grades:

Top Gem : no imperfections whatsoever, exceptional shine .

AAA (GIA) or A (SPP): The pearls present between 0 and 5%  of small surface imperfection, and excellent shine and orient. A very small, but deep imperfection is tolerated.

AA+ ( GIA) : The pearls present between 6 and 15%  of small surface imperfection, and excellent shinn and orient. A very small, but deep imperfection is tolerated.

AA (GIA) ou B (SPP): The pearls present between 15 à 25 % of small, natural surface imperfections, with a nice shine and orient. A very small, but deep imperfection is tolerated.

A+ (GIA) ou C (SPP): The pearls present between 30 à 40 % of small, natural surface imperfections, with a mediocre shine and orient. A maximum of 10% of the surface covered with deep imperfections is allowed.

A (GIA) ou D (SPP)  : The pearls present between 60 % of small, natural surface imperfections, with a poor shine and orient. A maximum of 20% of the surface covered with deep imperfections is allowed. The pearl may show parts of the nucleus.

Pearls below  A (GIA) or D (SPP) grade are not considered gems, and are not commercialized or exported.

To evaluate, classify and grade a cultured pearl, all these criteria need to be checked.
An important notion to understand is that a pearl needs to have its shape defined before being given a grade. It is completely possible for a button shaped pearl to have the same overall grade as a round pearl. So to properly identify and grade a pearl, one needs to first mention its shape, then its grade.
This is especially important for Tahitian circled pearls, on which the natural grooves are not considered to be imperfections.

Poemana guarantees the grade of each pearl it has, and certifies it with an authenticity certificate, describing the shape, size, color and the overall grade it recieved, according to the GIA system.