Cultured Pearls

What is a pearl, what are its characteristics?

A cultured pearl is a pearl formed by an oyster, composed of concentric layers of a crystalline substance called nacre deposited around an irritant purposely placed in the oyster’s body.

Natural pearls are formed by deposits of nacre around an irritant, which accidentally lodges within the body of an oyster. The value of the pearl comes from the unique ability of the crystalline nacre to absorb, refract and reflect light, imparting a distinctive quality, termed orient, to natural and cultured pearls.

Orient is the deep inner glow and shimmering iridescent characteristics of sea-grown pearls. The deeper the lustre and iridescence, the more precious the pearl.

Size contributes to the price of the pearl. As is it more difficult for oysters to grow large pearls they are more scarce. But two pearls of different sized may be valued the same if the smaller pearl is superior in orient.

Shape determines value too. The more symmetrical the shape, the more valuable the pearl. Examples of symmetrical pearls include – round, pear shape, tear shape and oval. Pearls of irregular and asymmetrical shape are termed baroque. Oysters grow pearls in many different shapes, from perfect spheres to long flat angle wing pearls.

Surface perfection contributes to value. The surface of a perfect pearl appears satiny smooth, but when viewed closely, natural or cultured pearls may appear to have irregular blemishes. You don’t need a magnifier to detect blemishes – when they are present, they are easily seen.

Rarity increases the value of any jewel. Cultured pearls themselves are relatively rare, as the pearl can only be developed in limited areas of the world’s oceans and take years to grow. A perfect pair of pearls is very rare because nature makes few pearls exactly alike in orient, shape and colour.

Types of Pearls

Akoya - one of the most familiar type of cultured pearls, they are grown in pearl oysters off the coast of Japan. Akoya pearls are known for their lovely orient and warm colour. They rarely grow more than 9mm in size.

Mabe – Large hemispherical cultured pearls grown against the inside shells of oysters instead of within the body. Less expensive than regular round cultured pearls and, because of their hemispherical shape, they are usually mounted in such jewellery as earring, rings and broaches.

Fresh Water – Pearls cultivated in molluscs, not oysters, found in fresh water lakes and rivers. Fresh water pearls generally are elongated in shape and have a milky translucent appearance. Their wide range of interesting shapes and colours make up in fashion appeal for their relatively low value. In China, shape and lustre are rapidly improving and round freshwater peals are readily available.

Keshi – Seedless pearls which form naturally in many cultured pearl oysters in both Akoya and South Sea Pearls. They also come in a variety of colours, shapes and sizes.

South Sea Pearls

Australian – Large cultured pearls (10mm and larger) grown in large oysters (called Pinctada Maxima) in warm waters off the Australian coast. These pearls are found in a variety of colours including white, silver, gold and rose. Australian South Sea pearls are generally rare and valuable. Also, in pristine waters of Shark Bay and the Abrolhos Island (off the coast near Geraldton) black pearls are grown in large oysters (Pintada Margaritifera). Colours include grey to black and hues from pink to blues and greens.

Indonesian – Large cultured pearls (10mm and larger), which are grown in large oysters (Pinctada Margaritifera – black lipped) off the islands of French Polynesia. Colours range from soft grey to black hues of reds, blues and greens.