Artificial gemstones

It is produced artificially for use as a gemstone, but it is relatively soft. Star sapphires and rubies exhibit their asterism as a result of the presence of Ti02. 

It is also used to make artificial gemstones and special glass and to make green colors in fireworks and flares. It formerly was used as a rat poison, but is no longer used for this purpose because it is very toxic to humans. 

Erel, E. Aubriet, F Finqueneisel, G. Muller, J.-F. Capabilities of Laser Ablation Mass Spectrometry in the Differentiation of Natural and Artificial Opal Gemstones. Anal Chem. 2003, 75, 6422-6429. 

Luminescence intensity with very rare exceptions is much higher in artificial gemstones compared to natural counterparts. It may be explained by the fact that the activator contents are usually higher in laboratory made gems, while the quenching center concentrations are lower. 

Lapis lazuli is a deep blue gemstone that is a complex copper silicate mineral varying widely in composition. It often contains sparkles of iron pyrite or calcite. The best source is probably Afghanistan. A pale blue variety is found in Chile. Some material sold as lapis lazuli is actually artificially colored jasper from Germany. 

There is hardly a better example to illustrate this than the case of ruby (AI2O3 Cr +). Ruby is a beautiful gemstone whose color varies from pale pink to deep red, depending on the chromium concentration. Artificial crystals are presently available. The cold fire of ruby—its deep-red luminescence—increases the attraction these crystals have for many people, not only scientists. 

Nassau, K. (1980) Gems Made by Man, Chilton Book Company, Radnor, PA. An excellent and highly readable account of the techniques used to produce artificial gemstones. Contains lots of history and background information on the processes and their inventors. 

The flame fusion technique (see Figure 7.20b) was originally devised in 1904 by Verneuil for the manufacture of artificial gemstones, such as corundum (white sapphire) and ruby. This method is now used for the mass production of jewels for watches and scientific instruments. A trickle of fine alumina powder plus traces of colouring oxides is fed at a controlled rate into an oxyhydrogen flame. Fusion occurs and the molten droplets fall on to a ceramic collecting rod. A seed crystal cemented to the rod is fused in the flame and the rod is lowered at a rate that allows the top of the growing crystal (known as a boule) to remain just molten. Renewed interest has recently been shown in this method for the production of rubies for lasers. 

Gemstones are very valuable materials, especially rare colored gemstones of certain types, such as deep blue diamonds like the Hope Diamond. Artificial stones and treated, dyed, and coated... 

Erel, E., Aubriet, F, Finqueneisel, G., Muller, J.F. (2003) Capabilities of laser ablation mass spectrometry in the differentiation of natural and artificial opal gemstones. Analytical Chemistry, 75, 6422-6429. 

Industry and Business. The discovery and distribution of gemstones is complicated and depends on the source and type of the gemstone. The De Beers Group has dominated the diamond market since the early part of the twentieth century, controlling most aspects of supply, distribution, and price. However, the discovery of diamonds in Russia, Australia, and Ganada and the creation of artificial diamonds for the industrial market has somewhat altered the market. 

Optical windows for high-temperature-high pressure reactors Scratch-proof watch glasses Ruby bearings for watches Artificial gemstones... 

A gemstone is a mineral that can be cut and polished to make gems for an ornament or piece of jewelry. At one time, all gemstones were naturally occurring minerals mined from Earth s crust. Today, however, chemists can duplicate natural processes to produce artificial gemstones. Amethyst, emerald, jade, opal, ruby, sapphire, and topaz occur naturally and can also be produced synthetically. 

In another variation, if vanadium ions, replace a few Al + ions in corundum, the result is a gemstone known as alexandrite. This gemstone appears green in reflected natural light and red in transmitted or artificial light. 

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