Apatite is a group of chemically similar minerals of the class of phosphates, arsenates and vanadates. Apatites are characterized by prismatic crystals and an intense colouring, which, however, only occurs when other substances are added. As pure minerals, apatites are almost colourless. Depending on the material and colour saturation, red, green, yellow, blue or yellow-green variants are possible, which give the translucent gemstone its unique characteristics and make it a popular and extremely precious gemstone. Because of its great sensitivity to acid and heat, processing is very difficult, which is why it costs more than other minerals. Even low heat or strong light can lead to colour changes. The hardness value of 5 (scratch test: can still be scratched with a knife) on the Mohs scale also requires special care when grinding the stone.