Citrine

Citrine is actually the same gem as Amethyst which is a variety of Quartz
The difference is Quartz with iron impurities will cause a purple color but if that iron oxidizes prior to crystalizing it will cause a yellow color, like rust then we call it citrine. Natural citrine can range from the traditional yellow to red. Citrine is one of the most faked gems in which a person heats an Amethyst burning the iron which will make it a amber color but that’s heated Amethyst, not Citrine which is rarer then Amethyst

Hardness: 7
Composition: SiO₂