Jargon Buster


Specific Gravity (SG)
The ratio of the mass of a substance to the mass of an identical volume of water at 4 degrees C
(By definition, the specific gravity of water is 1).

A phylum (mollusca) of soft-bodied, hard-shelled animals which includes cuttlefish, limpets, mussels, oysters, scallops & snails.

Pearl Doctor
A skilled technician who improves pearls by removing surface blemishes (see skinning).

This is a technique for improving the appearance of a badly coloured or blemished pearl by carefully polishing or filing away the outer layer.

The protective inner tissues of the pearl-producing mollusc which secretes nacre.

A secretion produced by the mantle of some molluscs, which forms the iridescent layers of both the pearl and mother-of-pearl surface inside the mollusc shell.

Mother of Pearl
The inner layer of the shell of some molluscs can be harvested and is known as Mother of Pearl. This is typically a thin layer in the shape of the shell and can in cases be very large. Most often used in large decorative jewellery.

Cultured Pearls
While cultured pearls may be very similar in appearance to natural pearls they are a lot cheaper for one simple reason. A very small piece of mother of pearl is placed inside a live oyster which will be in an oyster farm. This is left to grow and the natural secretions of the oyster will build up within the shell to produce a new pearl. Using this method it is easier to produce larger and more uniform pearls and also cheaper as no diving is required to find the molluscs.

Blister Pearl
In some cases the center of the pearl as it is first being formed will sit very close to the mantle. When such a pearl becomes larger one side of it will become fused to the mantle, as it grows further one side of the pearl will remain flat. Such pearls are often used in earrings, rings and brooches.