Ametrine

Related: Quartz Varieties

AgateAmethystAventurineBloodstoneCarnelianChalcedonyChrysopraseCitrineHawk's EyeOnyxPrasioliteRock CrystalRose QuartzSmoky QuartzTiger's Eye

Key Differentiators

• Distinct bicolor zones — purple amethyst and yellow/orange citrine in same crystal
• Quartz RI 1.544–1.553 and SG 2.65 — identical to amethyst and citrine
• Natural color boundary is curved or irregular; synthetic diffusion-bonded shows sharp planar junction
• Almost exclusively from Anahi mine, Bolivia
• Inert under both LW and SW UV fluorescence

Natural vs. Synthetic

Synthetic ametrine is commercially available (Hydrothermal growth (bicolor zones created by controlled growth conditions), Diffusion bonding (amethyst and citrine pieces joined under heat and pressure)). Distinguishing natural from synthetic typically requires microscopic examination of internal features.

• Microscopy — color boundary morphology: Natural ametrine shows an irregular, curved, or gradational color boundary between the purple and yellow zones, often with transitional mixed-color areas. Typical quartz inclusions (fluid inclusions, etch channels) present in both zones. Synthetic: Diffusion-bonded synthetic ametrine shows a sharp, planar (flat) color boundary at the junction of the two pieces — often perpendicular to the crystal axis. Hydrothermal synthetic shows straight parallel growth lines and may have a very abrupt color transition.
• RI and SG: RI 1.544–1.553; SG 2.65 — identical to all quartz. Synthetic: RI and SG are identical — these properties cannot distinguish natural from synthetic ametrine. Microscopy is essential.

Common Simulants

• Bicolor Glass: Bicolor glass may mimic ametrine but is isotropic (no birefringence), typically shows gas bubbles or swirl marks under magnification, and RI will not match quartz range.

Treatments

• Irradiation (artificial ametrine from citrine)
• Heat Treatment (shifts/modifies color zones)

Price Context

Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.

About Ametrine

Bicolor quartz variety with zones of purple (amethyst) and yellow-orange (citrine) in a single crystal. The zoning results from different iron oxidation states in different thermal zones during crystal growth. The Anahi mine in Bolivia produces virtually all commercial ametrine.