What is the difference between natural, South Sea, Freshwater and Akoya pearls?

June 3, 2015 / Lou Pike Pyman

So, what is the difference between natural, South Sea, Freshwater and Akoya pearls?

Natural Pearls:

A natural pearl is one that is formed in nature without any human intervention. A natural pearl forms when a foreign substance (for example, sand) makes its way into the shell of the oyster. As a ‘defence mechanism’ the oyster produces layers of nacre to protect itself from the irritating substance. These layers of nacre eventually form a pearl. The more scientific way to describe the process is:

1) Tiny irritants occasionally find their way into the body of an oyster. 2) Unable to expel the irritant, the oyster encloses the nucleus in a membrane or ‘pearl sac’. Layers of nacre form around the nucleus. 3) The result is a pearl with a unique combination of size, shape and colour.

Natural pearls are rare and fine quality natural pearls are even rarer, and therefore incredibly valuable. (Click here to read about the largest natural pearl found). The pearl necklaces shown below, are made up of matched natural pearls. The Baroda pearl necklace (below left) is valued at $7.1 million, with the five-strand natural strand necklace (below right) valued at $1.7 million. These are so valuable because the pearls are round in shape (considered the most prized), lack blemishes (imperfections), have even lustre (the shininess), and match in colour – most natural pearls are small, uneven in appearance with low levels of lustre while these are very fine quality.

All other types of pearls are produced with human intervention – they are classified as farmed or cultured :

South Sea Pearls

South Sea pearls are farmed in salt water, and the pearls are grown in a large oyster shell – the Pinctada maxima. They are mainly produced in Australia using wild oysters, and in Indonesia and the Phillipines using hatchery-reared oysters.

photo credit: pearlparadise.com

So, why are they so valuable? There are many factors that influence the high price of a South Sea pearl and many of them have to do with the oyster:

The Pinctada maxima oyster must reach 3-4 years of age before it can be seeded to produce a pearl.
Each oyster usually only produces a single pearl, with some rare oysters able to be seeded twice.
The seeding (the placing of the nucleus – a bead) of the oyster is a surgical procedure and must be carried out by an experienced technician.

photo credit: imperialpearl.com

Each single Australian South Sea pearl takes up to 2- 3 years to grow.
The colour of each pearl is determined by the mother-of-pearl interior of the oyster, and nature decides what the final colour of each pearl will be. The pearl can take on any colour from the inside of the shell of the oyster, but no colour ordering available! Because of this, it can take some time to create a strand of matched pearls.
The pearls range in size from 8 – 22mm.

photo credit: tripadvisor.com

Read here about the Australian history of pearl farming.

Tahitian Pearls

Tahitian pearls are grown in the same way as South Sea pearls, however they are grown in a very particular black lipped oyster – the Pinctada margaritifera. It’s the colour of the interior of the oyster that determines the colour and variety of the black and grey Tahitian pearls. Their name is derived from the general location of Tahiti, however the pearls are actually produced in the waters of French Polynesia.

The value of these beautiful pearls is again determined by their rarity – it’s reported that less than 5% of Tahitian pearls produced are considered gem quality.

photo credit: theonlinejeweller.com

Freshwater Pearls

Freshwater pearls are primarily farmed in China. They grow in a mussel (see below), as opposed to the oyster of the South Sea pearl. Freshwater pearls naturally grow in the Margaritifera margaritifera mussel, which can live for over 200 years, however these are now endangered. The Chinese production of freshwater pearls now occurs in a triangle shell mussel (Hyriopsis cumingii), and the nucleus is a living piece of mantle. There are many reasons that freshwater pearls are considerably lower priced than South Sea pearls:

photo credit: cnre.vt.edu

A single freshwater pearl mussel is capable of producing up to 50 pearls at a time (although current production limits each shell to 24-32 pearls).
The pearls are only left in the water for a maximum of 6 months.
Freshwater pearls are less likely to be blemish-free and round-shaped (considered the most valuable).
The pearls are often smaller in size.
The colour of the pearls is also determined by the interior of the mussel, however many freshwater pearls are dyed to produce their colour.

Watch this video for more…

Akoya Pearls

photo credit: purepearls.com

Mikimoto is the most famous name associated with Akoya pearls. It is reported that the first Japanese Akoya pearl was produced in 1893, with the first spherical pearl produced in 1905 following the relentless research of Kokichi Mikimoto. Akoya pearls are salt water grown in Japan, China and now India, and commonly range in size from 6-8mm.

The oyster used to grow Akoya pearls is the Pinctada fucata martensii. They are seeded with a round bead, made of mother of pearl, and a small piece of living tissue. This is how the predominantly round shape of Akoya pearls is achieved. There are usually only two pearls produced per oyster.

The popularity of South Sea pearls have affected the worldwide sales of Akoya pearls, however they are still popular and a beautiful strand of Akoyas will still cost thousands of dollars.

Please pop into the studio workshop if you would like to see and touch some of the pearls we have to view. We would love to show them to you.