Pearls were prized in ancient times, they were rare and only grew naturally in coastal ocean oysters, and in fresh water mussels in rivers and lakes. They were only affordable for the wealthy, royalty and the aristocracy.
By the 19th century natural pearls were overharvested and affected by industrial pollution. Around the turn of the 20th century Kokichi Mikimoto discovered how to cultivate pearls and democratized pearl ownership.
Cultured pearls grow the same way as natural pearls, but a bead is inserted into the oyster. The oyster surrounds the irritant with nacre, the same "mother of pearl" that lines the inside of the shell. The nacre builds up in layers around the bead forming the pearl.
Natural pearls tend to grow in the shape of the natural irritant, or nucleus, so perfectly round natural pearls are rare. For cultured pearls, technicians insert a round nucleus and can produce more rounded pearls.
Freshwater pearls are grown or cultured in freshwater mussels that live in fresh water lakes, rivers, ponds often in China. Saltwater pearls grow in oysters in the ocean, usually in bays. There are the three main types of saltwater pearls - Akoya, South Sea and Tahitian. Akoya is the name of the oyster we associate with the Japanese cultured pearls, although these are now grown in China, Vietnam and many other countries.
Holloway Diamonds rarely stock Akoya pearls these days; most have a very poor coverage of nacre because of industrial and agricultural pollution. We stock a range of fine high quality freshwater pearls that are more durable and long lasting than Akoya’s. These are not the cheap and nasty freshwater pearls you see for a few dollars - they are round and pinkish white with exceptional lustre.
South Sea pearls grow in tropical waters - the best of them from the crystal clean waters from Broome to Darwin. We have a lot of very fine silvery and pinkish silvery white pearls. The closer one gets to the equator, and the more pollution, the more likely pearls will grow in other colours, notably yellow to golden hues.
Tahitian and Cook Island pearls grow naturally in black to silvery grey colours because the beach sands in those islands are dark and rich with manganese.
Most pearls to be bleached, dyed or otherwise treated, except South Sea and Tahitian pearls. Japanese Akoya pearls are routinely bleached and dyed pinkish white. Other newer processes should be declared. e.g. Chocolate coating of pearls is a recent fashion treatment performed by several producers. The important thing is that these treatments are stable, durable and declared. A common illicit treatment is the filling of holes and blemishes with clear coatings; this is not a treatment that we approve of because they can wear off or dissolve and you will be very unhappy. Pearls are routinely cleaned and polished too.
The pricing factors are origin; shape (round, drop shaped, baroque etc); colour and overtone or secondary colour; lustre, which is a function of the nacre thickness; blemishes or pits and marks; and size in millimetres.