About Pearl Size | Tensei Pearl
About pearl size
Akoya pearls range from about 2.5mm to 10mm, and those over 10mm are extremely rare. Akoya pearls are generally sorted in 0.5mm steps, and this is reflected in the price.
South Sea pearls range from about 8mm to 20mm, and those over 14mm become rarer.
Size and rarity
The most commonly cultivated sizes are between 7 and 9mm. It depends on the year, but at the Uwajima auction of top-grade pearls, pearls over 10mm make up only about 5% of the total. Among them, those of good quality are even rarer. Even at the same size, the thickness of the nacre differs depending on the size of the nucleus inside. So for the same size, a pearl grown slowly from a small nucleus is more likely to be of high quality than one grown quickly from a large nucleus.
What is a pearl nucleus?
The nucleus is the core of a pearl. It is inserted inside the oyster, and the layers of nacre that build up around it become the pearl. Nuclei are made mainly by shaping into spheres the shells of a freshwater mussel that lives in the Mississippi River in the United States. Nuclei also vary in quality: perfectly round ones without blemishes, growth lines or color are considered best, and they raise the chance of a fine pearl.
About baby pearls
Baby pearls are small pearls of 5mm or less, and those of about 3mm are called "sairindama". Today few are cultivated, and as they become rarer, their prices tend to rise.
Despite the name, they are not baby pearls still growing; they are grown from extremely small nuclei. More than 100 pearls are needed to make one necklace, so top-grade necklaces are expensive.
(*There is no clear standard for the size of baby pearls, and it may differ from company to company.)
Why are South Sea pearls so large?
It is because of the type of oyster that grows them and where it lives. South Sea pearls are pearls produced by white-lipped and black-lipped oysters living in southern seas. White-lipped oysters with strong golden pigments produce pearls in the waters of Indonesia, the Philippines and Malaysia, while those with strong white pigments produce pearls mainly in the Arafura Sea off northern Australia. Black-lipped oysters are cultivated mainly in Tahiti, and the oyster itself has black pigment. These areas have very warm water, and the mother oysters themselves are several times larger than Akoya oysters.
White-lipped oyster from Australia
Akoya oyster from Japan
