Pearls Explained: Akoya, South Sea, Tahitian and Freshwater
Almost all pearls sold today are cultured: a bead or piece of tissue is placed inside a living mollusc, which coats it in layers of nacre over months or years. Japan pioneered the technique at the end of the nineteenth century and remains central to the pearl world. Understanding the main kinds of pearl, and how they are graded, is the key to buying well.
The four main kinds
- Akoya. Grown in a small oyster mainly in Japan. Usually 6 to 9 millimetres, round, with a mirror-like lustre and white, cream or silvery colour, often with a rose or green overtone.
- South Sea. Grown in a large oyster in the waters of Australia, Indonesia and the Philippines. Large, often 10 millimetres and more, in white, silver and gold, with a soft, satiny lustre.
- Tahitian. Grown in French Polynesia in the black-lipped oyster. Naturally dark, from grey to black with green, blue and aubergine overtones.
- Freshwater. Grown in mussels, mainly in China. Often solid nacre, in many shapes and soft colours, and generally more affordable.
How pearls are graded
- Lustre. The brightness and sharpness of reflections on the surface. The single most important factor.
- Surface. The fewer spots, bumps and pits, the better.
- Shape. Perfectly round pearls are rarest; baroque shapes have their own appeal and lower prices.
- Colour. The body colour and the overtone that floats over it.
- Size. Larger pearls of the same quality are rarer and more valuable.
- Nacre. Thick nacre gives depth and durability.
- Matching. In a strand, pearls should match closely in every respect.
Japanese certificates
Japan has a tradition of independent pearl certificates. The term hanadama, flower pearl, is used for top-quality Akoya strands that meet strict standards of nacre thickness, lustre and surface, and is issued with a certificate by a recognised laboratory. A certificate adds confidence and value, especially to a fine Akoya strand.
Genuine or imitation
Imitation pearls are made of glass or plastic with a coating. Gently rubbed against the edge of a tooth, real pearls feel slightly gritty, while imitations feel smooth. Look also at the drill holes, where coatings on imitations often flake, and at the weight: real pearls are heavier than plastic. A laboratory can confirm whether a pearl is cultured or natural.
Caring for pearls
- Put pearls on last, after perfume, hairspray and cosmetics, and wipe them with a soft cloth after wearing.
- Store them flat, apart from other jewellery, in a soft pouch.
- Have strands restrung every few years, with knots between the pearls, depending on how often they are worn.