Alexandrite is a chrysoberyl and belongs to the mineral group of oxides and hydroxides. The special feature of this gemstone, which was discovered in the middle of the 19th century and whose name goes back to the Russian Tsar Alexander II, lies in its unique play of colours. The colour gradient varies depending on the available light sources spectral colours. Due to its chrome content, alexandrite reflects the colours of the light. While natural sunlight causes the stone to shimmer green, artificial light tends to produce a shade of red. In different lighting conditions, a colour change from green to red can occur, which gives the alexandrite its unmistakable characteristic. This colour change is also known as the alexandrite effect.