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Synthetic Gemstones: Methods |
Some Method background . . .
Although Gaudin tried in 1837 - when Verneuil first discovered the secret of creating ruby, circa 1891 - 1904, he probably had no idea how far the various processes would develop.
Today there are a number of methods of creating gemstones. The most common is the process of Verneuil, which is flame fusion. Here the material is melted, using very high heat, and formed into "boules" somewhat similar in appearance to a candle. These are usually split to prevent cracking while cooling. Corundum (Sapphire and Ruby) and Spinel, are some of the materials created in this manner.
Diamonds are synthetically made but the process is quite expensive, and large stones of gem quality are rare. The General Electric Corp. is given credit for the first synthetically produced diamonds.A "Skull melt" process produces cubic zirconium. Low cost raw material and large volumes make the cost of these simulants very cheap. This material is not considered a synthetic because it has no counterpart in nature. In order to be called synthetic, a gemstone must have the nearly identical characteristics of the earth grown counterpart; hardness, refractive index, chemical and physical properties. In essence, it must be the same thing.
Ruby and Emerald are laboratory grown using seed crystals and a flux. This process is costly and takes a considerable amount of time to produce crystals large enough to cut gemstones.
The Czochralsky, or "pulled" method is used to produce materials used in the laser industry. This is a relatively expensive method, (compared to Verneuil) and is a much slower process. The advantage of this method is that the boules can be annealed and be much larger than with flame fusion. It is also a process that can be controlled more thoroughly to create virtually optically clear material.
Another method of producing high quality gemstones is the hydrothermal method. This is a process of growing gem materials much the same way they grow in nature. Emerald and Alexandrite are two of the gems grown in this manner.