Pearl Classifications:

The classification and value of Black Pearls are determined in accordance to criteria relating to luster, size, shape, surface, and colour.

Lustre:

Lustre is how light reflects or plays on and beneath the surface of the pearl. The aragonite layers of nacre absorb and reflect all types of light giving a pearl its hues and very occasionally a colour halo. A pearl with high luster is bright and extremely reflective. This quality is important as any color can be beautiful but exceptional luster is what will set a pearl apart.

Size:

In the Cook Islands, Pinctada Margaritifera produces pearls with an average size of 10-11mm. While sizes can reach 18mm, pearls of 13mm or more are rare and represent a small percentage of any harvest. The size is important in assessing its value due to the greater rarity of larger pearls. Pearl size is measured in millimeters, to the tenth. Even a 0.5mm difference in size between two large, rare pearls, of otherwise equal quality, can amount to thousands of dollars.

Shape:

The shape of a pearl depends very much on the shell and the whims of nature. In its efforts to rid itself of the irritating nucleus, a shell often turns and moves the object of its discomfort thereby creating many different shapes.

Click on the following pearl shapes to view examples:

Round, Semi-round, Semi-baroque (drop, button and pear), Baroque, and Circle.

Round Pearls:
Round pearls are almost perfect spheres whose diameter variation rate is less than 2%. The round pearl is the most sought after and the most rare of cultured black pearls.

When a pearl is allowed two years to grow inside an oyster, the chances of even, perfectly sphericalnacre accumulation are a long shot. Rounds rarely account for more than 10% of a pearl farm's crop while the norm is closer to 5%.

The percentage gets even smaller, when taking into account the many round pearls that are so heavily blemished they are unsaleable. Fine-quality round black cultured pearls are the most rare and expensive of the breed.

However, more plentiful semi-rounds and button shapes can give the look of round shapes for less money, especially when these pearls are set in jewellery. In such cases, slight deviations from round and even noticeable elongation can be concealed or, at the very least, masked.

Semi-round Pearls:

Semi-round pearls are slightly imperfect spheres whose diameter variation rate is greater than 2% but less than 5%.
A micrometer must be used to distinguish the difference between a round and semi-round pearl.

Semi-baroque pearls (Drop, Button & Pear):
Semi-baroque pearls exhibit at least one axis of rotation and are subdivided into three shapes: drop, button and pear. These symmetrical shapes are also highly prized.

                     Button                            Drop                               Pear

Baroque pearls:

Baroque pearls do not have any axis of rotation and are not symmetrical.

Given the transforming impact ofdesign on the look of a pearl, it is hardly surprising that black pearl specialists usually admire drop and baroque shapes.

Ringed or Circle Pearls:

Ringed, or circled, pearls are characterized by regular streaks, rings or grooves that are perpendicular to anaxis of rotation and cover more than a third of the pearl's surface.

Ringed pearls, which generally account for 25-30% of a black pearl harvest, seem to fire the imaginations of many designers.

No one knows why "circle pearls" occur so often in harvests. Whatever the cause of ringed pearls, they often compensate for this characteristic with pronounced color play and multiple hues.

Surface:

The more flawless a pearl is, the greater its value. "A" quality demands that blemishes or imperfections be confined to less than 10% of the pearl's surface. Pearls of this caliber however, are exceedingly rare. Minor imperfections are generally considered elements that give each pearl a slightly unique character.

Colour:

The colour of the pearl comes directly from the mantle of the shell, which secretes the nacre required to develop it. This mantle comes in many variaties of colour so the pearl a shell produces is not completely black.

The basic black or dark grey colours of the Cook Islands cultured black pearl combine with a multitude of hues such as: iridescent greens, ocean blues, pink/rose, golden, platinum or rainbow highlights.

All colours have their special qualities and individual taste should be the criteria for judging them.

Keshi Pearls:

Occasionally, the oyster will expel its nucleus, leaving the mantle tissue trapped inside the shell. In the absence of the nucleus, the mantle will continue to grow and secrete nacre creating a smaller, seedless Pearl known as Keshi. As with its larger cousin, the Keshi can vary in colour, shape and size. Keshi Pearls are very popular and can attain the value of some cultured Pearls.

The Pearl Guild:

The Pearl Guild and the Pearl Federation: In 1994 The Cook Islands Pearl Guild was established to develop and set comprehensive standards to safeguard the industry.
These policies include product verification to ensure that all industry criteria are met and adhered to thus protecting consumers at all levels.

All good retailers and wholesalers will display the Pearl Guild Logo.
Since its inception, The Pearl Guild has become synonymous with quality and is your international guarantee of quality. All Pearl Guild members supply recognised industry certificates.

The Guild works in close association with The Pearl Federation. Based in the Northern Cook Islands, the Federation is a collective body of farmers who provide a unified voice for producers and develop guidelines for the strategic growth, maintenance and development of the farming industry.

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