24.01.2022 Synthetic and artificial gemstones
Genuine gemstones are of high value and a good investment. But what does “genuine” actually mean?
Besides the general definition question of how to distinguish “gemstones” from “precious stones”, the question of genuineness is usually about natural gemstones vs. artificial “man-made” gemstones from the lab.
Recognize & determine real natural gemstones
Recognizing “real” gemstones, or correctly classifying a gem, is often challenging even for experts. While the trained eye of the specialist can distinguish gemstones from crude fakes or imitations, it can be complicated to determine a piece in terms of treatments or origin without laboratory analysis.
Ruby and spinel are always used as a classic example of how similar gemstones can look like. Until about 1800, people were not able to mineralogically distinguish red spinel from ruby.
It so happens that some of the most famous “rubies” on earth are actually spinels. One of the most prominent examples: The “Black Prince’s Ruby” in the British Imperial Crown is, contrary to what the name suggests, not a ruby at all, but precisely a red spinel.
Today, the distinction between the two gemstones is simple: spinel is single refractive, ruby is double refractive.
To be sure that you buy a natural gemstone, you should in any case buy only stones with the certificate of an independent gemological institute or laboratory. A gemstone certificate not only proves the mineral group, but also always states whether it is a natural gemstone or a lab grown synthesis, and also addresses the question of treatments or origin.
“Fake” gemstones: Imitation or synthesis?
The first distinction to be made with artificial gemstones is whether it is a synthesis or an imitation.
A gemstone synthesis is a crystal chemically identical to the natural stone, but which was produced in the laboratory. An imitation, on the other hand, is made of a different material, has a different chemical composition and/or different physical properties than the natural material being imitated.
Thus, a synthetic ruby is chemically a “real” corundum, while an imitation merely mimics the appearance of a gemstone. Imitations may be made of colored glass or may have been made of cheaper similar looking materials.
Synthetic Emeralds: Artificial Beryl
Initial work on the artificial production of beryl, and thus emerald, occurred as early as 1848, and emerald was then first synthesized on a commercial scale by a flux process in the 1930s by Jaeger and Espig at the IG Farben gemstone factory in Germany.
In the various processes, beryllium oxide, aluminum oxide, silicon oxide and lithium chromate (the latter for coloring), as well as fragments of natural emeralds are melted as base materials. Subsequently, new emerald crystals are formed around seed crystals during cooling.
Such syntheses can be distinguished from natural emeralds mainly by residues of flux in the stone and their general inclusion pattern.
Natural emerald also always contains water, syntheses made by the flux method are completely free of water, those made by the hydrothermal method contain water with properties different from naturally included water.
Therefore, the distinction between “natural” and “synthesis” in emerald is very easy to make in the laboratory.
Synthetic Ruby & Sapphire: Corundum out of the lab
Rubies and sapphires have also been artificially produced in the laboratory for nearly 150 years. The first synthetic corundum was made as early as 1877 by French scientist Edmond Fremy. Shortly thereafter, the chemist Auguste Verneuil developed a process to artificially produce corundum on a larger scale.
With the Verneuil Method named after him, synthetic rubies and sapphires can be produced in almost any color: from colorless to yellow, orange, green, blue and red.
In addition to the Verneuil Method, synthetic sapphire and ruby are also successfully produced using the flux methods and other technologies. The starting point for all methods is molten aluminum oxide, which then crystallizes out on so-called “seed crystals”. In the hydrothermal process, additional work is carried out under overpressure.
However, it is possible to distinguish lab grown minerals from natural corundum because synthetic corundum shows curved growth streaks, streaky color zoning, gas bubbles and inclusions of the flux used under the microscope.
Since the mid-1950s, it has also been possible to produce diamonds in the laboratory, although even the synthetic diamonds produced using the latest processes can be easily distinguished from the natural product by experts.
While synthetic diamonds were initially used mainly in industrial contexts, artificial “Lab Grown Diamonds” are now being used aggressively as increasingly inexpensive gemstones.
Buying synthetic gemstones?
Synthetic gemstones are mass produced and unlike natural gems, they have no special value. Therefore, they are suitable as a gemstone for jewelry but in no way as an investment.
If you want to buy gemstones as an investment, always purchase natural, untreated gemstones of the highest possible quality with certificates from internationally recognized gem labs and institutes.
The most interesting stones regarding are the big 3 cardinal color gemstones ruby, sapphire and emerald, which are not only stable in value, but from which you can expect considerable increases in value in the long term.