The origin of pearls is still a matter of growing interest and investigation. We know that broadly speaking they come from oysters and mussels. What we are not one hundred per cent sure of is what precisely it is that triggers the formation of pearls, since they are not the ‘normal’ product of an oyster but are the result of a morbid condition within the mollusc.
The condition which causes pearl production, i.e. their origin, has been the subject of much discussion. The earliest-known writings on pearls are, of course, not as scientific as those of the later centuries.
For hundreds of years much has been written in romantic/poetic vein, almost one might say in fairy-tale language. Traces of mumbo jumbo have lingered till the present day but fortunately, because of the pressures of science and the economic climate, research had to proceed and facts had to be ascertained.
Even though discussion continues, we know now that certain conditions do arise which cause pearl formation. The origin of pearls has been the subject of much speculation among sages, scientists and naturalists of all ages.
Needless to say, repetition of such opinions has perpetuated a considerable amount of misinformation and belief. See the timeline of various theories of the origin of pearls below.
| Author | Theory of cause |
|---|---|
| Aelian | Flashes of lightning |
| Rondeletius (1554) | Parasites and concretions |
| Various 16th century writers | Eggs of the mollusc |
| Redi (1671) | Grains of sand |
| Reaumur (1717) | Solidification of shell-forming liquids |
| Home (1826) | Abortion of an oyster egg |
| Kuchenmeister, von Hessling and Meckel (1856) | Parasites, sand, eggs |
| Moebius (1857) | Entozoa |
| Kelaart (1857-1859) | Sand, diatoms, eggs and parasites |
| Garner (1863) | Distomum, parasites |
| Comba (1898) | Parasites |
| Dubois (1901,1903) | Parasites |
| Jameson (1902) | Parasites |
| Herdman and Hornell (1902-06) | Parasites |
| Seurat (1902) | Parasites |
| Giard (1903) | Parasites |
| Boutan (1904) | Parasites |
| Rubbel (1911) | Shell substance |
| Jameson (1912) | Shell repair substance and perhaps parasites |
Pearls are tears
Although presently uncommon, pearls were believed to be derived from tears, during antiquity. The origin of the dogma ‘pearls are tears’ is unknown.
The pearls that long have slept. These were tears by Naiads wept
The Bride of Treamain, by Sir Walter Scott
Pearls are formed from dew
The idea that pearls are formed from dew is poetically shared Shakespeare.
The liquid drops of tears you have shed. Shall come again, transform’d to orient pearl.
Shakespeare
The Egg Theory
That pearls were formed from the eggs of oysters became another theory between the 15th and 17th centuries. Writing of Henricus Arnoldi as an eyewitness, Christopher Sandius wrote in a letter dated 1 December 1673: ‘Pearl shells in Norway do breed in sweet waters; their shells are like mussels but larger. The fish is like an oyster. It produces clusters of eggs.
These, when ripe, are cast out and become like those that cast them, but sometimes it appears that one or two of these eggs stick to the side of the matrix and are not voided with the rest. T
hese are fed by the oyster against her will and they do grow, according to the length of time, into pearls of different sizes.’ – Quote by Christopher Sandius
Intrusion Theory
Swedish naturalist Linnaeus, propounded the theory that pearl formation was caused by an intrusion into the soft body of mussels. Linnaeus in 1761 had some success in producing pearls by introducing into the mussel hard substances such as nacre and metal on a fine silver wire.
In some ways, the father of modern pearl cultivation, Kokichi Mikimoto received inspiration for his experiments, based on the ground breaking experiments of Linnaeus.
Parasite and sand-grain theory
With spherical pearls, which are cyst or sac pearls, the theory of a hard, intruded substance does not totally stand up to recent scientific scrutiny. Invasion of oysters by parasites is another widely accepted cause of pearl formation.
The sand grain or parasite becomes a focus of irritation in the oyster, leading eventually to pearl formation. Read this article on the process of pearl formation.
