What’s the difference between natural and cultured pearls?
Natural pearls, just as the name implies, are formed when irritants enter the oyster by accident. This is a pretty rare occurrence and doesn’t result in many jewellery quality pearls being available.
About 100 years ago a Japanese pearl farmer developed a process whereby a small piece of shell could be inserted into living Akoya oysters. These oysters were then put back into the water and the pearl forming process began. Today cultured pearls account for the majority of pearls used in jewellery.
Types of Pearls
Akoya pearls are primarily grown in the cool to temperate saltwater of Japan (China is the second largest producer) in the Pinctada fucataoyster species. This temperature allows the pearl to develop highly uniform mineral crystals resulting in brilliant lustre. Thus, many experts believe Akoya pearls have the highest lustre of all types. It takes between 8 and 24 months for a pearl to grow, although most farmers wait at least one year in hopes of a larger pearl. The size can range from 2 to 10 millimetre (average size is 6-7mm) and the colours are rose, silver/white, cream, gold and grey/blue.
Tahitian pearls are grown in the Pinctada margaritifera cumingi oyster species (also known as the Black Lipped Oyster) found throughout its native waters of French Polynesia. Only 1 in 10,000 of these oysters produces a pearl and because of this rarity they cannot be mass produced. It takes 22 to 26 months for a pearl to grow and the size ranges from 8 – 18 millimetres (average size is 9-10mm), but there are sometimes extremes; the largest Tahitian ever found was 25 millimetres! Tahitian pearl colour includes peacock (the most popular), black/black, black/grey, silver/grey, black/rose, black/blue, black/green and aubergine (eggplant).
South Sea Pearls
South Sea pearls are grown in the warm, pure waters off of Australia, Indonesia, the Philippines, Myanmar and Thailand in the oyster species Pinctada maxima (the two varieties are known as the Silver Lipped and Gold Lipped Oysters). These pearls (and their shells) are the largest and rarest grown. It takes 20 to 24 months to grow the pearl and there are many complications that can cause them to die. South Sea pearl size ranges from 9 â€“ 20 millimetres (average size 13mm) and their colours include silver, silver/pink, white, white/pink, white/gold and gold.
Freshwater pearls are formed in lakes, rivers, ponds and other freshwater bodies mainly in China (Japan and the U.S. also produce). Up to 40 pearls can be grown at once in one mussel (such as the Hyriosis cumingi) and for a long time there was much emphasis on producing large quantities, but today science has improved the farming techniques resulting in higher quality freshwater pearls. It takes 3 to 7 years for the pearls to grow and their size ranges from 3 – 13 millimetres (average size is 6mm). Freshwater pearls come in a variety of pastel shades including white, pink, peach, lavender, grey, yellow and cream.