Cut Oval-Shaped Citrine Gemstone
This is what happens when amethyst is heated.
The change in colour depends on the temperature and duration of heating.
Amethyst can turn yellow, green, brown, or colourless. It changes colour because heat alters the iron impurities and other trace elements in the crystal, which are responsible for its colour, and precise shade.
Amethyst is often heated to produce citrine, mainly because natural citrine is relatively rare.
A natural citrine gemstone of this size would not only be difficult to find, but would also be incredibly expensive.
Most natural citrine and citrine produced by heating amethyst comes from Brazil.