A member of the quartz family, amethyst - the distinctly violet gemstone - lends itself to lustrous rings, pendants and other jewelry. As a commonly synthesized stone, learning to identify the genuine article before you have the gem set into a band or necklace becomes especially important. While this task may ultimately call for the opinion of a jeweler with professional equipment, you can spot some key indicators of the real deal with your naked eye or a magnifying glass, depending on the size of the stone.
While genuine amethyst comes from the mines of Russia, Africa and South America, synthesized amethyst first appeared during World War II, produced by the process of hydrothermal crystal growth. This synthetic crystal replicates the violet color of the real thing very closely, meaning that a convincing base color alone is not a strong enough indication of natural amethyst. In fact, some varieties of synthetic amethyst can even replicate natural amethyst's color zoning -- an uneven distribution of color that gives gem stones deeper hues in some areas and lighter shades in others. However, color zoning in synthetic amethyst is typically more irregular, with a more stark difference between hues.
Holding an amethyst up to the light reveals many clues that can help determine whether the stone is natural or synthetic. When light filters through natural amethyst, it often creates a prism-like effect, which doesn't occur in synthetic varieties. Other features exclusive to natural amethyst include a feather- or fingerprint-like texture viewable on the inside of the quartz and the presence of light and dark bands known as tiger or zebra stripes. Likewise, natural amethyst sometimes features yellow-hued cacoxenite, which occurs as tiny, sheaf-shaped crystals within the stone.
As you consider this translucent stone under light and magnification, flaws serve as a key indicator of natural quartz; synthetic stones are often crystal clear while the real deal features small imperfections. In particular, inclusions indicate natural amethyst. Characteristic inclusions -- the presence of tiny trapped shards of stone, liquid or air -- look like specs of dust or dirt, tiny crumbs or very small bubbles. Synthetically produced manufactured stones typically lack this naturally occurring flaw -- if synthetic stones do have inclusions, the inclusions are usually not as irregular as they are in natural amethyst.
More to Know
In some cases, you need only ask your jeweler if a certain stone is natural or manufactured. However, the abundance of synthetic amethysts makes for a particularly sticky situation: The Lulea University of Technology and Jeweler's Circular Keystone both estimate that half or more of commercially available amethyst is synthetic and is often sold to unwitting jewelers as the real thing. As a result, it may be necessary to get a second opinion. A trained professional will be able to identify the presence of the seed crystal -- the crystal from which synthetics are grown -- within a synthetic stone. If you come across an exceptionally large and clear stone at an extremely low price, beware -- this stone has an increased chance of being synthetic.
- GemSelect: Amethyst Gemstone Information
- BJ Bead: How to Identify Natural Amethyst
- Canada Institute of Gemology: Inclusions in Gems and Minerals
- Lulea University of Technology: Distinguishing Between Natural and Synthetic Quartz
- GemSelect: Color Zoning in Gemstones
- Jeweler's Circular Keystone: Buying Amethyst Today
- GemSelect: How Do I Tell if an Amethyst or Citrine Is Synthetic?