Detecting Synthetic Quartz
Synthetic quartz produced by the hydrothermal method has become a common sight in the market, and we want to be sure that all the amethyst, citrine, ametrine and other types of quartz we sell is completely natural. Our customers trust us to accurately describe the gems we sell, and we take that trust very seriously.
As buyers, we have seen a lot of synthetic quartz offered for sale and we are reasonably good at recognizing the most obvious cases. Synthetic amethyst or citrine is often seen in extraordinarily large sizes with perfect clarity, offered at prices that are simply too good to be true. Natural amethyst or citrine will typically exhibit color zoning that will not be seen in the synthetic material. Synthetic ametrine is often found in colors that are not seen in nature; either the color is extraordinarily vivid, or there are hues such as blue and green, which do not occur naturally.
However, not all synthetic quartz is so obvious. Some of it looks just like natural quartz, which is not surprising, since it is real quartz (just not naturally occurring). Distinguishing natural from synthetic quartz is quite a challenge, even for gemology labs, especially with very clean specimens. Many gem labs will simply issue an "undetermined" verdict when analyzing a quartz sample, since they lack the expertise to reliably identify synthetic material.
The best labs use a combination of traditional analysis and advanced instruments to reach a definitive conclusion about a quartz sample. The traditional analysis looks for distinctive "breadcrumb" inclusions left by the seed crystal that is used to grow synthetic quartz; color zoning usually only found in natural quartz and the presence of so-called "Brazil twinning", which is typical of natural quartz crystals.
Infrared spectroscopy is used to graph the wavelengths of infrared light that the quartz absorbs. Synthetic and natural quartz usually exhibit distinctive patterns of absorption.
Though there is no single definitive test for quartz, performing a number of tests is almost always conclusive. The analysis is time consuming and somewhat expensive. However, we consider it worthwhile and have samples tested for all of the different types of quartz we sell. It is the only way we can be sure that we are selling only natural quartz.