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Rhinestones: Composition & Cleaning

RHINESTONES: Composition & Cleaning

Humans, and Magpies, love shiny, reflective, colored things, and since our earliest history, humans have created imitations. The Romans perfected the production of coloured glass pastes, and were notably skilled in reproductions of emerald and lapis lazuli.

Rhinestones acquired their name because they were originally rock crystals, gathered from the Rhine river and also gathered in some mountainous regions like the Alps.

In the 18th Century, in 1758, the Viennese goldsmith Joseph Strasser developed a vitreous paste, a heavy, very transparent flint glass colorless paste that could be cut; it superficially approached the sparkle of genuine diamonds. The products of this paste are called "strass stones".

The earliest versions of so-called imitation gemstones were made from this colorless vitreous paste compound composed of a silicate of potassium and lead combined with borax, alumina, and white arsenic.

The Alsatian jeweler Georg Friedrich Strass (French: Georges Frédéric Strass; 29 May 1701, Wolfisheim near Strasbourg - 22 December 1773) is credited as the inventor of imitation gemstones called "Rhinestones".

Georg Friedrich Strass modified Joseph Strasser's paste, using mixtures of bismuth and thallium to improve the refractive quality and adding combinations of metal salts to create colors.

Pigments added to this paste give any desired colour:

  • chromium compounds for red or green,
  • cobalt for blue,
  • gold for red,
  • iron for yellow to green,
  • manganese for purple,
  • and selenium for red.

Various methods of metal deposition (ways to coat decorative iridescent lead glass with a thin metal layer) were available at the time, and already in use, such as thin foil and vapor deposition.

Georg Friedrich Strass had the idea to imitate diamonds by coating the lower bottom side of lead glass using metal powder with a binder.

Today, "Rhinestones" and imitation gems are made from essentially this same 18th century vitreous paste formula.

This 18th Century original recipe for the colorless paste used to make the earliest Rhinestones is remarkably similar to today's modern commonly formulated compound, which according to the Encyclopedia Britannica (see below) is:

  • 300 parts of silica (silicon dioxide, SiO2),
  • 470 of red lead (a lead oxide, Pb3O4),
  • 163 of potassium carbonate (K2CO3),
  • 22 of borax (a sodium borate, Na2B4O7·10H2O)
  • and 1 of white arsenic (arsenic oxide, As2O3).

(end quote)

 

For your information: HOW TO CLEAN RHINESTONES

Because of the compound vitreous chemistry inherent in genuine Rhinestone paste, it reacts to the presence of copper. A greenish oxidate film forms on true Rhinestones in contact with copper, and with alloys of high copper content such as brass. This greenish oxidate film covering may be removed with a weak solution of Hydrochloric Acid. This won't affect the Rhinestone but it may cause any surrounding metal to loosen.

Hydrochloric acid is a clear, colorless, highly pungent solution of hydrogen chloride (HCl) in water. It's highly corrosive. It's a strong mineral acid with many industrial uses.

Hydrochloric acid is found naturally in gastric acid; when it reacts with an organic base it forms a hydrochloride salt. It was historically called acidum salis, muriatic acid, and spirits of salt because it was produced from rock salt and green vitriol (by Basilius Valentinus in the 15th century) and later from the chemically similar common salt and sulfuric acid (by Johann Rudolph Glauber in the 17th century). Hydrochloric Acid is also known as muriatic acid; muriatic means "pertaining to brine or salt", hence muriate means hydrochloride. Free hydrochloric acid was first formally described in the 16th century by Libavius. Later, it was used by chemists such as Glauber, Priestley, and Davy in their scientific research. The name hydrochloric acid was coined by the French chemist Joseph Louis Gay-Lussac in 1814.

 

From Wikipedia, the free encyclopedia: https://en.wikipedia.org/wiki/Georg_Friedrich_Strass:

(quote) Georg Friedrich Strass (French: Georges Frédéric Strass; 29 May 1701, Wolfisheim near Strasbourg - 22 December 1773) was an Alsatian jeweler. He is credited as the inventor of imitation gemstones. He is best known as the inventor of the rhinestone, called strass in many European languages, from a particular type of crystal he found in the river Rhine. He used mixtures of bismuth and thallium to improve the refractive quality of his imitations, and altered their colors with metal salts. The imitations were, in his view, so similar to real gems that he invented the concept of the "simulated gemstone" to describe them. He considerably improved his gems' brilliance by gluing metal foil behind them. This foil was later replaced with a vapor-deposited mirror coating. Strass opened his own business in 1730, and devoted himself wholly to the development of imitation diamonds. Due to his great achievements, he was awarded the title "King's Jeweler" in 1734. He was a partner in the jewellery business of Madame Prévot. He continued improving his artificial gemstones during this time. His work was in great demand at the court of King Louis XV of France, and he controlled a large market for artificial gems. Wealthy through his businesses, he was able to retire comfortably at age 52. (end quote)

 

Reference: Encyclopedia Britannica at http://www.britannica.com/art/paste-jewelry:

(quote) Paste, heavy, very transparent flint glass that simulates the fire and brilliance of gemstones because it has relatively high indices of refraction and strong dispersion (separation of white light into its component colours). From a very early period the imitation of gems was attempted. The Romans in particular were very skillful in the production of coloured-glass pastes, which copied especially emerald and lapis lazuli. With an increasing demand for jewelry, the number of imitations steadily increased.

In 1758 the Viennese goldsmith Joseph Strasser succeeded in inventing a colourless glass paste that could be cut and that superficially approached the sparkle of genuine diamond; the products of this paste are called strass stones.

Before 1940 most imitation gems were made from glass with a high lead content. Such glasses were called paste because the components of the mixture were mixed wet to ensure a thorough and even distribution.

Colourless paste is commonly formulated from:

  • 300 parts of silica (silicon dioxide, SiO2),
  • 470 of red lead (a lead oxide, Pb3O4),
  • 163 of potassium carbonate (K2CO3),
  • 22 of borax (a sodium borate, Na2B4O7·10H2O),
  • and 1 of white arsenic (arsenic oxide, As2O3).

Pigments may be added to give the paste any desired colour: chromium compounds for red or green, cobalt for blue, gold for red, iron for yellow to green, manganese for purple, and selenium for red.

Pastes are softer than ordinary or crown glass but have a higher index of refraction and dispersion that give them great brilliancy and fire. The cheaper paste imitations are pressed or molded, but, on the better-quality stones, the facets are cut and polished.

Molded-glass imitations can be identified with a hand lens, because the edges between the facets are rounded whereas cut glass has sharp edges.

Cut paste stones may be distinguished from real ones in several ways:

  • (1) paste has air bubbles, natural stones do not;
  • (2) paste is a poor conductor of heat, and so paste stones feel warm to the touch;
  • (3) paste, like all glass, has an easy conchoidal fracture, yielding brilliant curved surfaces particularly on the girdle (the widest part) of mounted stones near the mounting prongs.
  • Other differentiation methods involve hardness (paste is softer than real stones and will not scratch ordinary glass),
  • index of refraction (1.50–1.80, less than diamond at 2.42),
  • specific gravity (between 2.5 and 4.0, depending on the amount of red lead used),
  • and isotropic character (because paste has the same properties in all directions,
  • it shows only single refraction and no dichroism, whereas most natural stones are partially doubly refractive and dichroic).

(end quote)

For More Information:

  • http://www.britannica.com/art/paste-jewelry
  • https://en.wikipedia.org/wiki/Rhinestone
  • https://en.wikipedia.org/wiki/Hydrochloric_acid


We hope this information is helpful to you. Thanks for reading. Merci de votre visite. 

GALLERY:

  • Deux boucles de bottines en strass, années 1900 environ.
  • Brooch ancienne en métal avec pierres crystal sculpté, et velours de soie bleu; sans les poincons.



Strass Gallery
Deux boucles de bottines en strass, années 1900 environ.Brooch ancienne en métal avec pierres crystal sculpté.
Deux boucles de bottines en strass, années 1900 environ.Brooch ancienne en métal avec pierres crystal sculpté.
Deux boucles de bottines en strass, années 1900 environ.Brooch ancienne en métal avec pierres crystal sculpté.
Brooch ancienne en métal avec pierres crystal sculpté.Brooch ancienne en métal avec pierres crystal sculpté.
Hover over the small image to enlarge
 

 



All Content is © Debra Spencer, Suit Yourself™ International. Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved.
Please do not reproduce in part or in whole without express written consent. Thank you.

 

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All Content is ©2019 Debra Spencer, Appanage™at www.suityourself.international Suit Yourself ™ International, 120 Pendleton Point, Islesboro Island, Maine, 04848, USA 44n31 68w91 Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved. Please do not reproduce in part or in whole without express written consent. Thank you.

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All Content is ©2019 Debra Spencer, Appanage™at www.suityourself.international Suit Yourself ™ International, 120 Pendleton Point, Islesboro Island, Maine, 04848, USA 44n31 68w91 Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved. Please do not reproduce in part or in whole without express written consent. Thank you.
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