ametist

Ametist is a violet to purple variety of quartz used as a gemstone. In the jewelry trade, the term denotes a color range and may be sold as amethyst or amethyst-like material. The name Ametist is a modern spelling variant used in some markets.

Composition and structure: Ametist is chemically SiO2. It crystallizes in the hexagonal system as prismatic crystals and microcrystalline aggregates. Common properties include a hardness of 7 on the Mohs scale; a vitreous to pearly luster; a specific gravity around 2.65; and a refractive index near 1.54 to 1.55.

Color, treatment, and treatment: Natural Ametist ranges from pale lilac to deep violet, sometimes showing zoning or banding. Color is typically caused by trace amounts of iron and exposure to natural irradiation. In jewelry, color can be intensified or altered by heat treatment or irradiation; dyeing and coatings are uncommon and generally avoided on genuine stones.

Occurrence and mining: Ametist forms in silica-rich hydrothermal veins and pegmatites, often alongside quartz, feldspar, and mica. It is found in many regions worldwide, with crystals sold as loose stones or in geodes. Individual crystals can range from several millimeters to several centimeters in length.

Use and market: Cut and polished Ametist is widely used in jewelry, carvings, and decorative objects. Value depends on color saturation, clarity, and provenance; large, clean crystals are desirable but remain affordable compared with rarer gemstones. Synthetic Ametist produced by hydrothermal methods is also available and commonly used for beads and cabochons.