Produced in both ocean and freshwater molluscs, pearls are the only gemstone not formed on the Earth’s surface. Natural pearls are created when a miniscule foreign body, like a parasite or grain of sand, becomes stuck inside a mollusc. The mollusc attempts to defend and protect itself of irritants by forming a sac around the foreign body and building up layers of nacre (a calcium carbonate formula) around it. The more layers that build up, the larger the pearl gets, as well as the older it becomes. These factors affect the rarity and value of a pearl. This natural process is carefully imitated in controlled conditions to cultivate pearls both in freshwater mussel farms and saltwater oyster farms.
Cultured pearls come in many beautiful colours, from pale cream and white to rose, lilac, green, gold, grey, and black. There are four main types of cultured pearls: Akoya, South Sea, Tahitian, and Freshwater each having unique qualities that separates them for the other. The colour of naturally formed pearls ranges from white to pink, blue, brown, grey and black, depending on the type of mollusc and the water in which they are found.
Pearl is the birthstone for June and the gemstone of the 3rd and 30th wedding anniversaries.
Both natural and cultured pearls fall at a 2.5 on the Mohs scale of hardness. While the Mohs scale is mostly used to measure the hardness of mineral based gemstones, pearls are an exception as they are still an organically formed gemstone. Measuring a 2.5 on the scale means pearls are very soft and can be easily scratched, however, if looked after correctly and worn with care, pearl jewellery can be a long-lasting treasure.