South Sea pearls

A natural pearl is created over time when the oyster covers a small irritant like sand with layers of irridescent nacre. Cultured pearls are created in the same way, but the oyster is 'seeded' with a small sphere of shell which it then covers with layers of nacre. South Sea pearls are cultured pearls, grown in the renowned large Pinctada maxima oyster from the tropical waters around Australia. They are usually white, cream, pink, silver or gold.

Types of pearl

• Keshi: 'seed pearls' - small, interesting and irregular.
• Mabe: 'half' or 'blister' pearls: with flat backs suitable for brooches and special settings.
• Baroque: Irregular, unusual, modern jewellery pearls.
• Round: Spherical in shape - the most valuable pearls.

Choosing a pearl

To tell a real (natural or cultured) pearl from a fake, rub it against your teeth. A fake feels smooth, but a pearl created in an oyster will feel slightly rough due to the microscopic prisms of nacre. Pearls are graded on the 'five virtues':

• Lustre: the quality, depth and richness of the nacre and its irridescence.
• Colour: from the parent oyster - from whites to creams, silvers, pinks and golds.
• Complexion: the amount and quality of small natural markings ('movement').
• Size: the larger the pearl the more valuable it is.
• Shape: round, near-round, dropped, button, baroque, semi-baroque, and circle.