Laboratory-created stones, precious stones or synthetic, as the name suggests, are made in a laboratory. Synthetic gemstones have rarity of naturally colored stones and they are less expensive than naturally mined stones. The way they are made, synthetic gems may show subtle differences in shape and color that help to distinguish them from their natural counterparts. A synthetic gemstone is identical to a natural gem in almost any way. This includes the same basic crystal structure, refractive index, specific gravity, chemical composition, color and other characteristics.
Since the same gemological tests are used to identify natural and synthetic stone on stone, sometimes it is even possible as a gemologist to be confused on whether or not a natural or synthetic stone. Such stones can be made colorless or by using metal oxides, in more colors, and thus can be made to resemble many natural stones, including amethyst, diamond, spinel, emerald, opal and corundum (ruby and sapphire). Alexandria.
Lapis lazuli, turquoise, coral and produced by French manufacturer, Gilson, are similar to their natural counterparts, but are not really synthetic, because their optical and physical properties of different natural stones. Gilson Lapis Lazuli, for example, is more porous and has a lower specific gravity.
Methods of making synthetic gems
Growth from melt:
* Flame Fusion or Verneuil Process
Originally developed (1902) by a French chemist, Auguste Verneuil process produces a boule (a mass of alumina with the same physical and chemical characteristics, corundum) fine ground alumina (Al2O3), through an inverted oxyhydrogen torch that opens into a ceramic muffle. With slight modifications, this method is used to produce spinel, rutile, and strontium titanate.
The Verneuil method to make rubies, a rod with a seed crystal "" is melted and then lowered into the mineral brought back up. Repeating this process over and over grow a large crystal on the end of a bar of melted minerals. Rubin can be detached and then cut and polished.
* Close or Czochralski technique's
A synthetic crystal growth method of high melting point designed by Polish scientist Jan Czochralski, who discovered the method in 1916 while investigating the crystallization rates of metals. Czochralski and is called the Czochralski pulling technique. If a seed crystal is slightly reduced until it is in contrast to pure melt in the crucible and is then slowly pulled up. Product shows rod-like single crystals. Used to be rare-earth garnets, lithium Niobe, Scheel synthetic and synthetic alexandrite.
* Brigman-Stockbarger Technique
Method involves heating polycrystalline material in a container above its melting point and slowly cooling it from one end where a seed crystal is located. Single crystal material is progressively formed to along the length of container. process can be performed in a horizontal or vertical geometry.
Growth from solution:
* Method hydrothermal
Aquamarine and Quartz crystals are grown in a solution, autoclave, where temperature and pressure are controlled create feed material called lascas the hottest part. Seed crystals are colder portion that lascas redeposits forming synthetic quartz. This process may take 30 to 60 days, and is also used to increase the amethyst, citrine, or rock crystal.
* Flux Melt Method
Pioneering the French chemist Edmond Fremy, Flux-melt technique is still used to make emeralds. Powdered ingredients are melted and fused in a solvent (the flow) in a crucible. The material must be kept at a high temperature for months, before being allowed to cool very slowly.
* High Temperature / Pressure Method:
A type of growth solution in water at high temperature and pressure is known hydrothermal technique. Increasing the solution is achieved by an increase in saturation. As the addition of increasing amounts of sugar water, sugar, until it is dissolved solution is saturated and can absorb no more and then starts to re-crystallize. Cooled, crystallization will increase and heating will decline. A seed crystal is often employed to initiate crystallization and provide a point for submission to begin. Crystal growth rates are a function of time, temperature, and concentration. Hydrothermal techniques are used to Make emeralds, quartz, rock crystal and amethyst.
* Skull Melting Process
This process was perfected in the USSR in particular for shaping zirconia synthetic cubic to use in optical, electronic and laser equipment. Cubic zirconium oxide has a high melting point and is a very reactive. No container can hold the melt of zirconium, cubic has a melting point of 2750 ° C, and thus a cold crucible or skull is used.
Imitation stones may be formed of any substance such as glass, paste or strass, tile, porcelain, acrylic, and plastics. Ceramics are the most common and least expensive simulants and they are used as substitutes for many types of materials such as the popular Gem turquoise, coral, jade, pearls. Imitation stones are made for Gemstone simulate a particular, but they have the same chemical, and optical properties of natural gemstone, the gemstone synthetic and therefore can be easily distinguished from synthetic and natural Gemstones. Volcanic glass, a man-made substance of obsidian and Volcanic ash is a possible candidate for Aquamarine and Sapphire pale imitation. Some examples of imitation stones are cubic zirconia, synthetic moissanite (Diamond) and yttrium aluminum garnet which are diamond simulants. Since diamonds are so valuable and popular diamond market impostors is immense, and many additional simulants, such as zirconium, cubic, GGG, YAG, strontium titanate, synthetic rutile and were created moissanite in the last 50 years. Other stones are Emerald imitation doublet, sheet glass (opal), imitation Lapis Lazuli, synthetic Forster (Tanzania), synthetic Forster (peridot).
http://www.valuablestones.com/imitation.htm
The trail of three precious gems- Ruby, Sapphire, Emerald.
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