Synthetic vs natural green amethyst

The main feature of amethyst, and this feature has made it possible for a larger production of synthetic green amethyst, is its ability to change color under proper conditions. When we say proper conditions we refer to the well know property of amethyst to suffer from color degradation when heated above certain temperature. In most of the cases amethyst's wondrous violet color turns yellow when the stone is heated. This is well known to the gem manufacturers who make use of this fact to produce artificial citrine (yellow quartz) starting from raw amethyst. To produce citrine, the stone producer would need a temperature of around 620 K to 820 K, which would result in change of color from violet to yellow or to some nuances of amber or brown-yellow. Further increase in temperature would lead to significant deprivation in color, resulting in milk-like, opaque appearance. I will give you an example - If you happen to come across citrine geodes, and especially if they are inexpensive, make sure that they are not produced artificially from amethyst geodes. The naturally occurring citrine geodes are very rare.

However, some amethyst specimens from some regions of the world exhibit color change towards green, instead of towards yellow. This was rather surprising development for many jewel producers to see that the geographic origin of the gemstones can largely affect the results of their treatment. Therefore the conclusion was reached that if the proper conditions are applied ( and these conditions might apart from heat treatment include irradiation) the green color of this gemstone can be obtained. Due to this fact, in the recent years, we are faced with increased amount of synthetic prasiolite on the markets. Also some amount of synthetic green quartz has also find its way to penetrate the market offering inexpensive replacement for the genuine green amethyst - prasiolite.

The way prasiolite has been produced in nature is basically the following. Several hundreds milion years ago, rock crystal has been produced from igneous stones. The rock crystals that contained some iron within them, created defect centers, so called color centers, which in combination with our planet's radiation can be held responsible for giving the violet color to amethyst. Now, during time these amethyst crystals could have been occasionally heated, and thus by participation in natural processes they turned into citrine, and occasionally the color of this beautiful green variation of quartz. From this we can see that we are faced more or less with the same process - heating and radiation - regardless of whether the stone in naturally produced or artificial.

There is however one method suitable for distinguishing naturally produced prasiolite from the synthetic counterpart. By applying emerald filter, the green amethyst obtained artificially looks reddish, whereas the genuine prasiolite retains its color. The emerald filter has been invented to discriminate genuine emerald stones from the synthetic gemstones. This filter transmits only the ruby red and green areas of the visible light spectrum. As the artificially produced green amethyst transmits more in the ruby red part of the spectrum it appear reddish through this filter. The natural stone transmits higher intensities in the green region of the spectrum, therefore retaining its green color from the other side of the filter.

Another problem is production of synthetic green quartz, among the other multicolored types of silica minerals. Multicolored quartz produced artificially possesses some unusual crystals habits. In order to keep the crystal growth rate high, that is to produce the synthetic quartz crystals faster, as well as to produce larger specimens, crystal growers prefer certain axes as directions in which the crystal grows more rapidly. These crystal axes are not preferred in Nature, and due to this fact the discrimination of artificial greened amethyst is more easy. On the other hand, before producing jewelry, the crystals are cut and refined which again prevents discrimination.

Therefore, the only advice that can be given if you want to buy genuine jewelery produced from this gemstone is - always buy greened amethyst from reliable sources.