How to recognize fake pearls and stones

Beware of imitation jewelry and how to recognize them.

Today, more and more precious stones or pearls that adorn jewelry are being imitated, and the cleverest cannot recognize the deception. It is enough for them to be worn casually for people to believe they are real. This fact is so well-known that we see high society ladies or actresses resorting, out of fear of theft, to wearing fake diamond jewelry while keeping their precious jewels in safes. Since the pleasure of exhibiting jewelry often lies in being admired and, above all, a little envied, the desired result is achieved nonetheless.

The most targeted precious stone by fraudsters is, naturally, due to its high commercial value, the diamond. The base of most of its imitations is a special glass called strass, which owes its high refraction to the presence of about 50% lead oxide in its composition. It was already known in the Middle Ages - if not even before - and was used for the same purpose as today.

By adding traces of coloring substances, most other precious stones are also imitated: rubies (10% antimony glass, 1% cassius purple, and excess gold); sapphire (25% cobalt oxide); topaz (40% antimony glass, 1% cassius purple); emerald (8% copper oxide and 0.2 chrome oxide); amethyst (25% cobalt oxide and some manganese oxide); garnet (with a variable amount of cassius purple, depending on the desired shade). As for aventurine, it is imitated with a glass based on potash, soda, lime, and magnesia, colored yellow by iron oxide and containing a large number of fine copper oxide flakes in suspension; the resulting product is valued at 30 to 150 francs per kilogram, depending on its beauty. (1930)

In the same fraudulent purpose, "double stones" are used, which are composed of a genuine stone on top and strass underneath. The line of separation of the two masses is concealed in the jewelry. Sometimes, the stone is entirely made of strass, but a reflective layer similar to that in mirrors is placed underneath, reflecting light rays towards the upper facets.

fake pearls in the past

Easy-to-recognize altered stones

Another widespread type of fraud is passing off low-value stones as high-priced ones. Since transparent or differently colored hyaline quartz is very common in nature, stones that resist filing perfectly (which many people mistakenly believe is characteristic of a real stone) can be obtained at very low prices, displaying a remarkable range of colors admired in genuine gemstones.

It was even believed at the beginning of the Middle Ages that topazes and rubies could be transformed into real diamonds under the influence of transmutation ideas prevalent at the time. To "whiten" a sapphire, it is enough to wrap it in chalk and gradually subject it to intense heat: it is then slowly cooled to obtain a completely discolored appearance resembling a diamond.

However, what is most imitated today are fine pearls, whose delicate and ethereal appearance would seem to be immune to fraud.
The industry of fake pearls, dating back to 1680, is unanimously attributed to a rosaries and religious objects manufacturer, a "patenotrier" as they were called then, named Jacquin, residing in Passy. Numerous attempts may have been made before, but no chronicle mentions them, and Jacquin remains the inventor of this industry that soon became a veritable source of wealth. It is very prosperous in France and Italy, employing many workers.

how to make fake pearls

The fake pearl industry

The fake pearl industry gives rise to two different types of work: the manufacturing of glass spheres and the preparation of the essence that Jacquin had called "essence of the Orient." The glass spheres are made by enamelers using capillary tubes called "girasols." The girasols must have a diameter as uniform as possible along their entire length to ensure symmetry in the necklaces. Producing pearls in a pear shape and skillfully imitating deformed or baroque pearls is also feasible through irregular inflation.

To make the "essence of the Orient," scales of shiners or other fish of the same kind are subjected to several water washes with added ammonia to prevent decay. The scales are then crushed under water, decanted, mixed with a gelatinous liquid, and about seven pounds of scales are needed to obtain approximately one pound of essence of the Orient. This essence is spread evenly on the sieve to form a well-distributed layer. After drying, the cavity of the sphere is filled with melted white wax. The so-called fine pearls are also imitated by cutting balls from beautiful mother-of-pearl, rolling them in a paste made of gum and pulverized mother-of-pearl - known as "Rome pearls."

Achieving the same result with simple glass balls slightly etched on the surface using fluorhydric acid is also possible, as this acid is one of the few that can attack glass.