Tumbled ametrine from Bolivia with the characteristic violet-gold bicolor zoning. The only mineral on the planet that combines amethyst and citrine in a single piece, from the Anahí mine—the only known natural ametrine deposit in the world.
Piece Specifications
| Mineral |
Ametrine (bichrome quartz with Fe²⁺/Fe³⁺ in distinct growth sectors) |
| Dimensions |
Variable · Freeform ±0.5 mm |
| Shape and Back |
Tumbled, rounded freeform |
| Finish |
Drum polished (satin-gloss) |
| Hardness |
7 Mohs — resistant to everyday use |
| Origin |
Bolivia (Anahí Mine, Santa Cruz) |
| Treatment |
Untreated. The bicolor zoning is natural due to differences in iron oxidation state in sectors of the same crystal. |
| Type of Piece |
Individual piece — each tumbled stone has its own proportion of violet and gold zones |
These Specific Tumbled Stones
The proportion between the violet and gold zones varies in each piece. Some tumbled stones show the transition as a sharp diagonal stripe; others present a more diffuse gradient. This variation is not a defect: it reflects the orientation in which the drum cut the original crystal with respect to the contact plane between the two oxidation sectors.
Drum tumbling produces a particularly interesting finish on ametrine because continuous polishing reveals the color transition at different depths: the contact zone is visible on the surface; when rotating the piece under grazing light, its transparency allows for an intuition of the internal color distribution.
Why Ametrine Only Exists in Bolivia
Ametrine is the result of a very specific geological condition that has only been found naturally in the Anahí mine, in the department of Santa Cruz (Bolivia). During the growth of a quartz crystal, different parts of the same crystal were exposed to varying temperature and pressure conditions. In areas where iron partially oxidized to Fe³⁺, the quartz was colored violet (amethyst); in areas of slightly higher temperature where Fe²⁺ predominated, the color is yellow (citrine). The boundary between both zones can be abrupt or gradual depending on the speed of the condition change.
Uses of Tumbled Ametrine
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Mineralogical collection — one of the few natural bichrome gemstones in the world, with a single documented geographical origin.
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Wire wrap — the violet-gold color transition creates a very attractive visual effect in wrapped pendants; the piece "tells its own story" depending on how it is oriented.
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Gift for collectors — the rarity of the Bolivian origin makes it a piece with narrative as well as aesthetic value.
Ametrine in Lapidary Tradition
The Anahí mine has a documented history since the 17th century: according to Jesuit chronicles, a Spanish conquistador received the mine as a dowry upon marrying Anahí, a Bolivian princess, and the first gemstones arrived in Europe during that period. The mine was commercially rediscovered in the 1970s, and since then Bolivia has been the only recognized world producer of natural ametrine.
The symbolic properties attributed to minerals belong to cultural and historical traditions. They are shared for educational purposes, not as medical advice or a substitute for professional care.
How to Recognize Genuine Ametrine
Genuine ametrine has a color transition with natural variations in thickness and irregularities along the contact plane. Artificial or partially heated ametrine shows a uniform horizontal separation band without irregularities. Under a 10× loupe, genuine ametrine exhibits microinclusions typical of hydrothermal growth in both zones. Imitations in dyed glass have flat colors without the depth of quartz.
Frequently Asked Questions
Is ametrine dyed or treated?
No. The bicolor zoning is a result of natural crystallization conditions in the Anahí mine, with no detectable subsequent treatment.
Why does the color proportion vary between pieces?
The proportion between the violet and gold zones depends on the angle at which the drum cut and rounded the stone.
Is it suitable for wire wrapping?
Yes. Its hardness of 7 protects it from normal wear. The violet-gold color transition creates a highly sought-after visual effect.
