Pearls and Organics

Where most gemstones are generally of mineral origin, a few gems, known as organics, come from plants like amber and from animals like pearls and coral.

Pearls have been used for personal adornment since antiquity. Formed in oysters and mussels as a natural defence against an irritant, they build what is called the nacre consisting of layers of aragonite and conchiolin. Nowadays it is almost impossible to find natural pearls. Cultured pearls are essentially the same, where human intervention has inserted the nucleus. The production of whole cultured pearls was started in 1890 by Kokichi Mikimoto of Japan.

Pearls are valued by their translucence, lustre, play of colour and shape. Pearl colour varies with the mollusc and its environment, namely the chemistry of the water it resides in. Pearl colour is established by a combination of:

• Body Colour, the predominant basic colour of the pearl
• Overtone, the one or more colours that overlie the body colour
• Orient, the combination of sheen, lustre and iridescence showing a play of lustrous colours that may be like those of the rainbow or a subtle combination of colours such as pink, blue green and silver

Colours of Pearls:

• A Rose colour is considered an exceptional colour by most
• Persian Gulf pearls are cream and are also called Oriental Pearls
• Australian pearls are white with greenish or bluish shades; those with high lustre are defined as Silvery
• Tahiti, South Seas, Burma or Island Pearls are usually large, white with only a slight overtone, also yellow, gray, black with greyish metallic cast.

Clarity in pearls is described on surface characteristics by appearance, texture, purity, complexion, flawlessness, etc…

More about Pearls:
Most saltwater pearls are found in pearl oysters in oceans, seas, gulfs and bays. Freshwater pearls are found in mussels in rivers, lakes or ponds and tend to be more irregular in shape and varied in colour. Japan, northern Australia and Fiji are major producers of marine cultured pearls. The Mississippi River is a major site of freshwater cultured pearls production.

Pearl varieties and trade names are described by place of origin, body colour, overtone, orient and shape, such as:

• Oriental Pearls
• Akoya Pearls
• Biwa Pearls
• South Sea Pearls
• Mikimoto Pearls and more...

Major sources for cultured pearls are Japan, China, South Seas (Australia, Burma, Philippines, Tahiti), United States, Coasts of Polynesia and for freshwater pearls Scotland, Ireland, France, Austria, Germany and the United States.

Imitation pearls are made from glass or plastic beads coated with a paste made from fish scales. Other pearls are those produced by snails and abalone in colour combinations of shades of green, blue, pink, purple and silver. A pearl with peach, brownish or white tones with a porcelain-like surface is called conch.

Caring for pearls:
Pearls are sensitive to acids, dryness and humidity and therefore it is important to keep them clean. The quality of a pearl depends on the thickness and lustre of the nacre, the amount of orient present and the colour, roundness and freedom from blemishes.

Other important organic gems are:

Coral: a polyp, the skeletal remains of a marine animal. It can be red, pink, white and blue, whereas black and golden corals are a conchiolin. Red coral is the most valuable and has been used in jewellery for thousands of years.

Amber: fossilized resin of trees. The most famous deposits are in the Baltic region. The colour typically ranges from golden yellow to golden orange, transparent to translucent, and may contain insects and other small organisms trapped millions of years ago while the resin was still sticky.

Ammolite: fossilized shells of ammonite presenting play of colour in blue, green, and red.