A-Z of Gemstones: P

Posted on the 4th November 2016

A-Z of Gemstones: P: Pearl, Peridot

PEARL

Although natural pearls do exist, they are so rare to find today that they are usually extremely valuable. 

When we talk about pearls we usually refer to the four types of cultured pearls which are: Akoya, South Sea, Tahitian, and Freshwater.

Akoya pearls mostly have round, near-round, oval, button and baroque shapes and they range from 6 to 7mm and occasionally they come in smaller or larger sizes. They usually have a neutral to near-neutral white and cream colour with pink or green overtones. Dyed Akoya pearls might be pink, yellow or blue.

South Sea pearls mostly have round, near-round, oval, button and baroque shapes and they range from 8 to 15mm. They come in near-neutral white, cream, yellow, yellowish orange, blue, green with rose-coloured overtones.

Tahitian pearls mostly have round, near-round, oval, button and baroque shapes and they range from 8 to 14mm. They are usually black, grey, silver, cream, brown, blue, green, yellowish green with green, blue or purple overtones.

Freshwater pearls offer the widest variety of pearl and come in many different shapes and any size between 2 and 13mm and almost every colour.

Two more desirable natural varieties of non-nacreous pearls are Conch and Melo pearls which come in cream, yellow, orange and pink. The Conch pearls are very valuable and are they praised for their “flame-structure” iridescent sheen.

Pearls are translucent to opaque and they mostly cut as fully-drilled or half-drilled beads.

Pearls rate 6.5-7.0 on the Mohs scale so they are mostly suitable for jewellery such as brooches, necklaces and earrings. They are, however, vulnerable to chemical damage such as perfumes so you should always apply a spritz before you put on your pearls!

The main sources of cultured pearls are: Australia, Philippines, Indonesia, Tahiti, Cook Islands, Fiji, Japan, China

Pearls are commonly dyed or irradiated to create more desirable colours.

Materials that are mostly used to imitate pearls are glass and plastic.

Pearl is the June birthstone.

 

PERIDOT

Peridot is the gem variety of the mineral olivine.

Peridots’ colour range is very limited; they only come in light to dark yellowish greens which are caused by the presence of iron.

Peridots are relatively clean stones but they occasionally have a typical disk-like liquid and gas inclusion known as “lily-pad”.

Peridot lustre is vitreous; it rates 6.5-7 on the Mohs scale which makes it suitable only for jewellery that has secure settings to protect the stone from wear.

The main sources of peridot are: Myanmar, Pakistan, Arizona in the U.S.A. and China.

There are no known treatments for peridot and it has not yet been lab synthesised.

Some materials that are commonly used to imitate peridots are: glass, plastic and triplets.