Artificial Pearls

Those round calcareous 757  excrescences found both in the bodies and shells, especially on the nacreous coat, of several kinds of shell-fish 758 , have been much used as ornaments since the earliest ages 759. The beautiful play of colours exhibited on their surface has raised them to a high value 760 ; and this they have always retained on account of their scarcity and the expense arising from the laborious manner in which they are collected 761. By the increase of luxury among the European nations, the use of pearls has become more common; and even in Pliny's time they were worn by the wives of the inferior public officers, in order that they might vie in the costliness of their dress with ladies of the first rank. It is probable, therefore, that methods were early invented to occasion or hasten the formation of pearls; and as at present those who cannot afford to purchase gold, jewels, and porcelain, use in their stead pinchbeck, artificial gems, and stone-ware, so methods were fallen upon to make artificial pearls.

The art of forcing shell-fish to produce pearls was known, in the first centuries of the christian æra to the inhabitants of the coasts of the Red-sea, as we are told by the philosopher Apollonius, who thought that circumstance worthy of particular notice. The Indians dived into the sea, after they had rendered it calm and more transparent by pouring oil into it. They then enticed the fish by means of some bait to open their shells; and having pricked them with a sharp pointed instrument, received the liquor that flowed from them in small holes made in an iron vessel, in which they hardened into real pearls 762. Olearius says that this account is to be found in no other author: but it has at least been copied by Tzetzes 763.

We are as yet too little acquainted with shell-fish to be able to determine with certainty how much truth there really may be in this relation: but there is great reason to conjecture from it that the people who lived on the borders of the Red-sea were then acquainted with a method of forcing shell-fish to produce pearls; and as the arts in general of the ancient Indians have been preserved without much variation, the process employed by the Chinese at present, to cause a certain kind of mussels to form pearls, seems to confirm the account given by Philostratus. In the beginning of summer, at the time when the mussels repair to the surface of the water and open their shells, five or six small beads, made of mother-of-pearl, and strung on a thread, are thrown into each of them. At the end of a year, when the mussels are drawn up and opened, the beads are found covered with a pearly crust, in such a manner that they have a perfect resemblance to real pearls. The truth of this information cannot be doubted, though some experiments made in Bohemia for the same purpose were not attended with success 764. It has been confirmed by various persons 765 , and it is very probable that some operations and secrets, without which the process would prove fruitless even in China, may be unknown to the Europeans. Besides, many observations are known which seem to show the possibility of such an effect being produced. Fabricius says that he saw in the possession of Sir Joseph Banks, at London, large Chamæ766 , brought from China, in which there were several bits of iron wire, incrusted with a substance of a perfect pearly nature 767. These bits of wire, he said, had been sharp, and it appeared as if the mussels, to secure themselves against the points of the wire, had covered them with this substance, by which means they had been rendered blunt. May not therefore the process employed by the ancients be still practised? And may not these bits of wire have been the same as those spikes used by the people in the neighbourhood of the Red-sea for pricking mussels, and which perhaps slipped from the hands of the Chinese workmen and remained in the animals?

The invention therefore of Linnæus cannot be called altogether new. That great man informed the king and council in the year 1761, that he had discovered an art by which mussels might be made to produce pearls, and he offered to disclose the method for the benefit of the kingdom. This however was not done, but he disposed of his secret to one Bagge, a merchant at Gottenburg, for the sum of eighteen thousand copper dollars, which make about five hundred ducats. In the year 1780, the heirs of this merchant wished to sell to the highest bidder the sealed-up receipt 768 : but whether the paper was purchased, or who bought it, I do not know; for Professor Retzius at Lund, of whom I inquired respecting it, could not inform me 769. In the year 1763, it was said in the German newspapers, that Linnæus was ennobled on account of this discovery, and that he bore a pearl in his coat of arms; but both these assertions are false, though Fabricius conjectures that the first may be true 770. Linnæus received his patent of nobility, which, together with his arms, I have seen, in the year 1756, consequently long before he said anything respecting that discovery, of which the patent does not make the least mention. What in his arms has been taken for a pearl, is an egg, by which M. Tilas, whose business it then was to blazon the arms of ennobled families, meant to represent all nature, after the manner of the ancient Egyptians. The arms are divided into three fields, each of which, by the colour forming the ground, expresses one of the kingdoms of nature; the red signifying the animal, and the green the vegetable, &c. Over the helmet, by way of crest, is placed the Linnæa 771 ; that beautiful little moth the Phalæna linneella, shining with its silvery colours, is displayed around the border instead of festoons; and below is the following motto, Famam extendere factis. Linnæus once showed me, among his collection of shells, a small box filled with pearl, and said, “Hos uniones confeci artificio meo; sunt tantum quinque annorum, et tamen tam magni.” “These pearls I made by my art, and though so large they are only five years old.” They were deposited near the Unio margaritifera, from which most of the Swedish pearls are procured; and the son, who was however not acquainted with his father's secret, said the experiments were made only on this kind of mussel, though Linnæus himself assured me that they would succeed on all kinds.

I conjecture that Linnæus alluded to this art in his writings so early as the year 1746, or long before he ever thought of keeping it a secret. The passage I mean is in the sixth edition of his Systema Naturæ, where he says, “Margarita. Testæ excrescentia latere interiore, dum exterius latus perforatur 772.” I once told him that I had discovered his secret in his own works; but he seemed to be displeased, did not inquire after the passage, and changed the discourse. That pearls are produced when the shells have been pierced or injured in a certain manner, is highly probable, and has been in modern times often remarked 773. It appears also, that the animal has the power of sometimes filling up such openings with a calcareous substance, which it deposits in them. This substance assumes the figure of the orifice, and the animal particles it contains give it its brightness and lustre 774. Pearl-fishers have long known that mussels, the shells of which are rough and irregular, or which exhibit marks of violence, commonly contain pearls, though they are found also in others in which the same appearances are not observed 775. I am perfectly aware that some experiments made by piercing the shells of mussels, have been unsuccessful 776 ; but this does not prove that it is impossible to procure pearls in that manner. Those who made them did not perhaps pierce the proper part of the shell; perhaps they made the orifice so large that it weakened the animal; and they may not have chosen the fittest season of the year. The strongest objection however which can be made on this subject, is the undeniable truth that the proper valuable pearls are not found adhering to the shell, but in the body only; and that therefore those calcareous balls which fill up holes, cannot be perfect pearls. But from the words of Linnæus above-quoted, I am led to conjecture, that he only made a hole in the shell without piercing it quite through. Linnæus also may have done some injury to the animal itself when it opened its shell; for it is certain that testaceous animals are strong-lived, and can easily sustain any violence. It appears by the Transactions of the Swedish Academy, that some have been of opinion that shell-fish might be made to produce pearls by a particular kind of nourishment; and Lister 777  thinks that these excrescences would be more abundant, were the mussels placed in water impregnated with calcareous matter; but Professor Linnæus seems certain that his father employed none of these methods.

Under the name of false or artificial pearls are understood at present small beads, so prepared by art as to approach very near to real pearls in shape, lustre, colour, and polish. It appears that in Pliny's time such were not known, else he certainly would have mentioned them. The invention was not easy, and this difficulty to imitate pearls has contributed, with the reasons before mentioned, to keep up their value. It would seem that at first, hopes were entertained of finding a method to make large pearls from small or broken ones. Tzetzes speaks of this imagined art, and receipts for that purpose have been still retained in various books, where they fill up room and amuse the ignorant; for it is hardly possible to give to the pulverised calcareous matter sufficient hardness, and that lustre which belongs only to the surface of real pearls, and which, when these are destroyed, is irrecoverably lost. More ingenious was the idea of making pearl-coloured glass beads of that kind called margaritini 778 ; but it excites no wonder that this was not done earlier, although the art of making coloured glass is very old; for opal colours are obtained only by a skilful process and the addition of putty, bone-ashes, and other substances. Still earlier was the invention of making hollow glass beads, which were incrusted on the inside with a pearl-coloured varnish. This method was first pursued, as far as I have been able to learn, by some artists at Murano; but their invention seems to have been considered by the government as too fraudulent, and was therefore prohibited, as we are told by Francis Massarius, who lived in the beginning of the sixteenth century at Venice, and must therefore have had an opportunity of knowing the truth of this circumstance 779. Some say that an amalgam of quicksilver was used for these pearls; and if that was the case, the object of the Venetian prohibition was rather of a medical nature. After this, small balls of wax or gum were covered with a pearl-coloured enamel. These were praised on account of their lustre; but as their beauty was destroyed by moisture, they did not continue long in use 780. A French bead-maker, however, named Jaquin, at length found out the manner of preparing the glass pearls used at present, which excel all others, and which approach as near to nature as possible, without being too expensive.

Jaquin once observed, at his estate near Passy, that when those small fish called ables  or ablettes  were washed, the water was filled with fine silver-coloured particles. He suffered this water therefore to stand for some time, and obtained from it a sediment which had the lustre of the most beautiful pearls; and which on that account led him to the attempt of making pearls from it 781. He scraped off the scales of the fish, and called the soft shining powder, which was diffused in the water, essence of pearl, or essence d'orient 782 . At first he covered with it small beads made of gypsum, or hardened paste; and, as everything new, particularly in France, is eagerly sought after, this invention was greatly admired and commended. The ladies, however, for whose use it was chiefly intended, soon found that it did not entirely answer their expectations. They were displeased because this pearly coat, when exposed to heat, separated from the beads, adhered to the skin, and gave it a brightness which they did not wish. They proposed themselves, that small hollow glass beads might be covered, in the inside, in the same manner as mirrors are silvered, with the essence of pearl; and thus was brought to perfection an art of which the following account will enable the reader to form some idea.

Of a kind of glass easy to be melted, and made sometimes a little bluish or dark, slender tubes are prepared, which are called girasols 783 . From these the artist blows, by means of a lamp, as many small hollow globules as he may have occasion for. One workman can in a day blow six thousand; but when they are required to be extremely beautiful, only twelve or fifteen hundred; and that they may have a greater resemblance to nature, he gives them sometimes blemishes, like those generally observed in real pearls. They are made on all figures; some shaped like a pear, others like an olive, and some that may be considered as coques de perles 784 . To overlie these thin glass bubbles he mixes the pearl essence with a solution of isinglass; and the more of the former he uses, the more beautiful and more valuable the pearls become. This varnish, when heated, he blows into each globule with a fine glass pipe, and spreads it over the whole internal surface, by shaking the pearls thus prepared in a vessel placed over the table where he is at work, and which he puts in motion by his foot, until the varnish is equally diffused all over the inside of them, and becomes dry. Sometimes he adds to the essence some red, yellow, or blue colour; but as this is a deviation from nature, it is not accounted a beauty. To give these tender globules more solidity and strength, they are filled with white wax. They are then bored through with a needle, and threaded in strings for sale. The holes in the finer sort, however, are first lined with thin paper, that the thread may not adhere to the wax 785.

The name able, or ablette, is given to several species of fish; but that which produces the pearl-essence is the Cyprinus alburnus, called in English the bleak. Professor Hermann, at Strasburg, was so kind as to send me one of these fish, which was caught there for the purpose of making pearl-essence, and which was dried so carefully that the species could with certainty be distinguished. It corresponded exactly with the figure given in Duhamel 786 , which has almost a perfect resemblance to that given by Schoneveld 787. May not the alburnus  mentioned by Ausonius among the inhabitants of the Moselle, be the same? At any rate, the bleak is to be found only in fresh water; and on account of its voracity bites readily at the hook. It is caught for the use of the French manufacturers in the Seine, the Loire, the Saone, the Rhine 788 , and several other rivers. To obtain a pound of scales above 4000 fish are necessary; and these do not produce four ounces of pearl essence; so that from eighteen to twenty thousand are requisite to have a pound of it. In the Chalonnois, the fishermen get for a pound of washed scales fifteen, eighteen, and twenty-five livres. The fish, which are four inches in length, and which have not a very good taste, are sold at a cheap rate, after their scales have been scraped off. At St. John de Maizel, or Mezel, in the Chalonnois, there was a manufactory in which 10,000 pearls were made daily 789.

The first makers of these pearls must have laboured under a very great inconvenience, as they were acquainted with no method of preserving the fishy particles for any time. They were obliged to use the essence immediately, because it soon putrefied and contracted an intolerable stench. The great consumption, however, required that the scales should be brought from distant provinces. Attempts were made to preserve them in spirit of wine or brandy; but these liquors destroyed their lustre, and left them only a dull white colour. In the like manner brandy spoiled a real pearl, which, with the animal and the shell (Mactra lutraria ), was sent to me by Dr. Taube, at Zell. It was therefore a very important discovery for this art that these animal particles can be kept for a long time in solution of ammonia, which is now alone used, and which perhaps could be used for many other purposes of the like kind.

That the inventor of these pearls was called Jaquin, and that he was a bead-maker at Paris, all agree; but the time of the invention seems to be uncertain. Some say that it belongs to the reign of Henry IV.790 ; and Reaumur mentions the year 1656. These pearls, however, in the year 1686, when Jaquin had an assistant named Breton, must not have been very common; for we are told in the Mercure Galant of that year, that a marquis possessed of very little property, who was enamoured of a lady, gained her affections and carried his point by presenting her with a string of them, which cost only three louis; and which she, considering them as real ones, valued at 2000 francs. The servant who put the marquis on this stratagem, declared that these pearls withstood heat and the moisture occasioned by perspiration; that they were not easily scratched, had almost the same weight as real ones, and that the person who sold them warranted their durability in writing. Jewellers and pawnbrokers have, therefore, been often deceived by them. Jaquin's heirs continued this business down to a late period, and had a considerable manufactory au Rue de Petit Lion at Paris.


757  It was because pearls are calcareous that Cleopatra was able to dissolve hers in vinegar, and by these means to gain a bet from her lover, as we are told by Pliny, 1. ix. c. 35, and Macrobius Saturn. 1. ii. c. 13. She must, however, have employed stronger vinegar than that which we use for our tables, as pearls, on account of their hardness and their natural enamel, cannot be easily dissolved by a weak acid. Nature has secured the teeth of animals against the effects of acids, by an enamel covering which answers the same purpose; but if this enamel happen to be injured only in one small place, the teeth soon spoil and rot. Cleopatra perhaps broke and pounded the pearls; and it is probable that she afterwards diluted the vinegar with water, that she might be able to drink it; though dissolved calcareous matter neutralizes acids and renders them imperceptible to the tongue. We are told that the dissipated Clodius gave to each of his guests a pearl dissolved in vinegar to drink:—“Ut experiretur in gloria palati,” says Pliny, “quid saperent margaritæ; atque ut mire placuere, ne solus hoc sciret, singulos uniones convivis absorbendos dedit.” Horace, lib. ii. sat. 3, says the same. That pearls are soluble in vinegar is remarked in Pausanias, b. viii. ch. 18, and Vitruvius, b. viii. ch. 3.

758  That pearls are not peculiar to one kind of shell-fish, as many believe, was known to Pliny. I have a number of very good pearls which were found by my brother in Colchester oysters. It is more worthy of remark, and less known, that real pearls are found under the shield of the sea-hare, (Aplysia ), as has been observed by Bohadsch in his book De Animalibus Marinis, Dresdæ, 1761, 4to, p. 39.

759  In the time of Job, pearls were accounted to be of great value. Job, chap. xxviii. ver. 18.

760  [When the surface of pearl is examined with a microscope, it is found to be indented by a large number of delicate grooves, which by their effect upon the light give rise to the play of colours; and if impressions of them be taken upon wax, fusible metal, lead, balsam of Tolu, &c., the impressed surface exhibits the prismatic colours in the same manner as the pearl. This principle has been applied by Mr. Barton and others to the making of ornaments, in the form of buttons, artificial jewels, &c., by grooving the surface of steel with a very fine cutting machine. The theory of the production of the colours is this: the surfaces of the grooves, from their varied inclinations, reflect the incident white light at various angles, hence the correspondence of the luminous undulations is interrupted and some of them check or interfere with one another, others continue their course. Now, ordinary white light being a mixture of coloured rays, when some of these are checked or interfered with in their progress, the remainder continue their course and appear of that colour which results from the ocular impression communicated by them.]

761  [One of the most remarkable pearls of which we have any authentic account, was bought by Tavernier at Catifa in Arabia, a fishery famous in the days of Pliny, for the enormous sum of £110,000. It is pear-shaped, regular, and without blemish. It is rather more than half an inch in diameter at the largest part, and from two to three inches in length.—Waterston's Encyclopædia of Commerce.]

762  Philostrat. in Vita Apollon. lib. iii. cap. 57, edit. Olearii, p. 139. Conrade Gesner, in his Hist. Nat. lib. iv. p. 634, gives a more correct translation of the passage.

763  Tsetzes Variorum, lib. ii. segm. 373.

764  See Dr. Joh. Mayer's Bemerkungen, in the fourth part of Abhandlungen einer Privatgesellschaft in Böhmen, p. 165.

765  Abhand. der Schwed. Akadem. der Wissenschaften, vol. xxxiv. p. 89. The author of the paper alluded to had a mussel with such artificial pearls, which had been brought from China. It was a Mytilus cygneus, the swan-mussel, or great horse-mussel. Mention is made also in Histoire de l'Académie des Sciences de Paris, année 1769, of a stone covered with a pearly substance which was found in a mussel.

766  A kind of cockles.

767  J. C. Fabricius Briefe aus London, Dessau, 1784, 8vo, p. 104.

768  See Schlözer's Briefwechsel, number 40, p. 251.

769  Dr. Stœver, in his Life of Linnæus, vol. i. p. 360, says that the manuscript containing this secret was in the possession of Dr. J. E. Smith, at London.—Trans.

770  In his Letters, p. 104.

771  This pretty plant, named after the father of botany, grows in Northumberland and some woods in Scotland, also in Switzerland, Siberia, and Canada, but particularly in Norway and Sweden, in shady places amidst the thick woods. The flowers, which appear in May, June and July, are shaped like a bell, rose-coloured without, yellowish in the inside, and somewhat hairy. They have a pleasant smell, especially in the evening. In Tronheim and the neighbouring parts they are drunk as tea for medicinal purposes.

772  Pearl. An excrescence on the inside of a shell when the outer side has been perforated.

773  See Chemnitz's theory of the origin of pearls, in the Beschäftigungen der Berlin. Naturforsch. Gesellschaft, i. p. 348.

774  The animal part is rendered evident on distillation by the evolution of an ammoniacal odour and a somewhat inflammable oil; and on solution in muriatic acid the animal substance is left behind.

775  Abhand. der Schwed. Akad. iv. p. 245, and xxi. p. 142.

776  Fabricius, in his Letters, p. 105, mentions such an experiment, which was however continued only for a year.

777  Exercitatio Anatom. de Cochleis. Lond. 1694, p. 183.

778  This manner of preparing margaritini  may be seen in my Anleitung zur Technologie, p. 307.

779  Massarii in Plinii Nat. Hist. lib. ix. Castigationes. Bas. 1537, 4to, cap. 35.

780  Mercati Metallotheca, p. 211.

781  These silver-coloured particles were examined by Reaumur, who gave a description of them in Histoire de l'Académie, année 1716, p. 229. [In the scales of fishes, the optical effect is produced in the same manner as in the real pearl, the grooves of the latter being represented by the inequalities formed by the margins of the concentric laminæ of which the scales are composed.]

782  The artist no doubt had in view eastern pearls.

783  Girasol. This word, which is wanting in most dictionaries, signifies opal, and sometimes that stone called cat's-eye, Silex catophthalmuspseudopalus, &c. Couleur de girasol  is applied to semitransparent milk-white porcelain.

784  Coques de perles  are flat on one side, and are used for ornaments, one side of which only is seen. By Pliny they are called physemata. Artificial pearls of this kind have, for some time past, been employed in making ear-rings. Our toymen, after the French, give these pearls the name of perles coques ; but the following account of Pouget in Traité des Pierres Précieuses, Paris 1762, i. p. 20, makes me dubious respecting them. “La coque de perle,” says he, “is not formed in a pearl-shell like the pearl; it is procured from a kind of snail found only in the East Indies. There are several species of them. The shell of this animal is sawn in two, and one coque  only can be obtained from each. The coques  are very small, and one is obliged to fill them with tears of mastic to give them a body, before they can be employed. This beautiful snail is found generally in the sea, and sometimes on the shore.” May not Pouget here mean that kind of snail which others call burgeau, the shells of which are, in commerce, known by the French under the name of burgaudines ? Should that be the case, the animal meant would be the Nautilus Pompilius, as may be concluded from Histoire des Antilles, par Du Tertre, ii. p. 239. For the author says, “C'est de leur coque que les ouvriers en nacre tirent cette belle nacre qu'ils appellent la burgaudine, plus estimée que la nacre de perle.” Irregular pearls are called baroques, or Scotch pearls, because abundance of such were once found at Perth in Scotland. Some years ago artificial pearls of an unnatural size, called Scotch pearls, were for a little time in fashion.

785  A complete account of the art of making glass pearls is contained in a book, which I have however not seen, entitled, L'Art d'imiter les perles fines, par M. Varenne de Beost. An extract from it may be found in Dictionnaire des Arts et Métiers, par M. Joubert, iii. p. 370. See also the articles perle  and able  in the Encyclopédie, i. p. 29; xii. p. 382.

786  Traité Générale des Pesches, par. ii. p. 403, tab. 23, fig. 1 et 2.

787  Ichthyologia, Hamb. 1624, 4to, p. 12, tab. 1, fig. 2, albula.

788  In the Almanach de Strasburg for 1780, p. 76, among the commodities sold there were, Des écailles d'ablettes dont on tire l'essence d'orient employée pour les fausses perles.

789  Déscription Hist. et Topogr. du Duché de Bourgogne, par M. Courtépée, tom. iv. A Dijon, 1779, 8vo, p. 534.

790  Pouget. 4to, i. p. 19.