In later times, imitations of precious stones were made of melted rock crystal, today they are made of special glass. It is a mixture of lead oxides, silicon, potassium carbonate and borax, which is drowning, casts, and then grinds until it is in the form of a jewel.
The composition of this mixture was developed by the Viennese Strasser, and gems made of this glass are called rhinestones. Pure rhinestones are used to produce imitations of colorless diamonds. When we want to obtain an imitation of colored stones, metal oxides are added to the molten glass, pure metals or other elements. Depending on the chemical composition, the conditions of glass melting and the type and amount of the coloring additive, a wide variety of tints of any shade can be obtained. Only some examples are given in the table.
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When we want to create opaque stones, we add a small amount of zinc, and when we want to increase the refractive index in colorless stones, increase their resemblance to a "fire-throwing" diamond, lower imitation surfaces or luminaire surfaces (e.g.. the ring) it is covered with a shiny light-reflecting film.
The list of colors includes, among others. a ruby color obtained by coloring the glass with a powder, and essentially atomized to colloidal size with gold. This glass was used to make an imitation of grenades. But the recipe for making these "stones” was invented at least twice. It was first done by the German alchemist Johann Kunkel in the 17th century. In his time, glass was so expensive, that even not every king could afford jewelry made of glass grenades. Kunkel, however, took his secret to the grave, and in his will he wrote: “Because it took so much trouble and worry to solve this secret, let no one blame me, that I do not make it public property ".
Years after Kunkel's death it turned out, that it is almost as easy and not much more expensive to make real grenades by fusing natural aluminosilicates with some metals at high pressures of the order of 3 do 4 MPa. However, the method invented by Kunkel was not forgotten. Gold-tinted glass, called golden ruby, still applies today. Even cheaper glass has been invented, copper ruby, dark cherry in color. Beautiful are made of these glasses, ruby glass vases, cups and other utensils worthy of royal tables. Both are used to coat the surface of crystal glass in order to obtain a two-color effect after polishing the patterns.
At the beginning of the 18th century, a new one was built, a center for the production of artificial gems in the Czech Republic, known to this day. In Turnów, two Fiszer brothers invented a glass mass other than strass, with its optical properties resembling precious stones. Through 50 For years, Turnowo was known on the markets of Europe and America for the production of glass stones, polished by excellent masters, stones, which often eclipsed the Venetian ones.
In the middle of the 18th century, the secret of the Fiszer brothers found their way to Jablonec nad Nisou and gave rise to a new company, known today as Jablonex. Its products are getting to 25 different countries, including to Poland. But Jablonex products are not imitations. This jewelry does not mimic anything. Using only the laws of physics, light optics, transparency and a wide range of glass colors, creates its own designs and its own fashion. Millions of such artificial stones are produced today by factories in England, Czechoslovakia, France, Italy and the USSR.