Peridot is a semi-precious stone composed of iron and magnesium and the iron is what causes its beautiful green coloring. It is unique in that it only appears in one color – green. Peridot is also unique in that its color does not change even under artificial light. Peridot is also known as chrysolite and olivine. Peridot is one of the three August birthstones. The other two are spinel and sardonyx. For more interesting facts on peridot, feel free to read our blog on August birthstones.