Ametrine Identification Guide
How to identify ametrine, the natural bicolor purple-and-gold quartz, by its sharp color zoning and quartz properties, and distinguish it from dyed imitations.
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What Ametrine Looks Like
Ametrine is a single quartz crystal that contains both amethyst (purple) and citrine (golden-yellow to orange) in the same stone. The hallmark is a sharp, often straight boundary between a purple half and a golden half, reflecting growth zones that took up iron in different oxidation states. Luster is vitreous, and quality material is transparent. Most ametrine reaches the market as faceted gems cut to display both colors side by side, though rough crystals show the zoning along their length.
Step-by-Step Field-ID Checklist
- Look for two colors in one stone — purple and yellow/orange, not blended into a single hue.
- Examine the color boundary. Natural ametrine shows a crisp, often angular or straight zone line following crystal growth planes.
- Confirm quartz hardness (Mohs 7) — scratches glass, resists a knife.
- Check fracture — conchoidal, glassy, with no cleavage.
- Rotate under light to confirm the colors are internal and zoned, not a surface coating or backing.
Key Diagnostic Tests
- Mohs hardness: 7.
- Streak: white.
- Cleavage/fracture: none; conchoidal fracture.
- Specific gravity: ~2.65.
- Refractive index: ~1.54–1.55 with low birefringence, like all quartz.
- Non-magnetic, inert to acid.
Common Look-Alikes
- Amegreen: also bicolor quartz but pairs purple with green prasiolite rather than golden citrine.
- Assembled or dyed quartz: dye and color coatings concentrate at the surface and in fractures; a loupe will show color pooling in cracks instead of clean internal zoning.
- Synthetic ametrine: grown commercially and physically identical to quartz; suspiciously perfect, repeating color zoning and total lack of inclusions can hint at synthetic origin, though lab testing is the only certainty.
- Heated/irradiated citrine alone: single-color, no purple zone — not ametrine.
Where It Is Found
Virtually all natural ametrine comes from a single famous source: the Anahí mine in eastern Bolivia, where the bicolor zoning forms naturally in hydrothermal quartz. Smaller amounts are reported from Brazil. The Bolivian origin and natural straight-zone boundary are the strongest indicators of genuine, untreated ametrine.
Frequently asked questions
How can you tell if ametrine is real?
Genuine ametrine is Mohs 7 quartz with conchoidal fracture and no cleavage, showing a sharp natural boundary between purple amethyst and golden citrine. Dyed imitations show color pooled in cracks or on the surface rather than in clean internal growth zones.
What does ametrine look like?
It looks like a glassy, transparent quartz with one purple region and one yellow-to-orange region in the same stone, usually divided by a clean, often straight color line.
Ametrine vs ametrine imitation glass — what's the difference?
Glass imitations contain bubbles and swirl marks, are softer than Mohs 7, and show blended or coated color. Real ametrine is harder, breaks conchoidally, and shows distinct crystallographic color zoning.
Where does natural ametrine come from?
Almost all natural ametrine comes from the Anahi mine in Bolivia, with minor reported occurrences in Brazil. A Bolivian source with crisp natural zoning is a strong authenticity signal.
Ametrine identified by the community
Recent Ametrine specimens identified with Rock Identifier.
