An interesting fact about natural bi-color ametrine is that it is one of the few gemstones that occur in nature with two distinct colors due to a unique twin formation. Ametrine is essentially a combination of two quartz varieties: amethyst and citrine. This unique gemstone is formed when different parts of a quartz crystal experience varying temperatures during its growth process, leading to the presence of iron in different oxidation states within the crystal.
The temperature gradient is key: one part of the crystal must be exposed to higher temperatures, which causes the iron impurities to induce the golden-yellow color of citrine, while the cooler part retains the purple color of amethyst. As a result, you get a striking color zoning that is naturally segmented within the same crystal, rather than intermixed.
Ametrine is primarily sourced from the Anahí Mine in Bolivia—often referred to as Bolivianite in reference to this—and it is so closely associated with this location that it is sometimes called ‘Bolivian ametrine’. It’s a testament to nature’s artistry, creating a gemstone with this kind of dual coloration without the need for human intervention or enhancement.
