Historical information

It is thought that natural pearls form under a set of accidental conditions when a microscopic intruder or parasite enters a bivalve mollusc and settles inside the shell. The mollusc, irritated by the intruder, forms a pearl sac of external mantle tissue cells and secretes the calcium carbonate and conchiolin to cover the irritant. This secretion process is repeated many times, thus producing a pearl. Natural pearls come in many shapes, with perfectly round ones being comparatively rare.
In general, cultured pearls are less valuable than natural pearls, whereas imitation pearls have almost no value. Cultured freshwater pearls can often be confused for natural pearls
Cultured pearls are the response of the shell to a tissue implant. A tiny piece of mantle tissue (called a graft) from a donor shell is transplanted into a recipient shell, causing a pearl sac to form into which the tissue precipitates calcium carbonate.
Some imitation pearls (also called shell pearls) are simply made of mother-of-pearl, coral or conch shell
A strand of pearls called a princess length, 43 to 48 cm in length, comes down to or just below the collarbone. A graduated strand of pearls most often has at least 3 mm of differentiation from the ends to the centre of the necklace.

Physical description

A lady's pearl necklace and 1 earring in a hinged, lined, cream Bakelite case .