The colour of a gemstone is a decisive characteristic for the quality or the price of a gemstone. For different gemstones, different colour nuances are regarded as high quality. In the general view, the colour of gemstones is measured according to different criteria. The first important clue when it comes to determining the colour of a gemstone is the distinction between its own colour and that of a foreign colour. Is a crystal, which is used for the jewellery, thus by its crystal structure characteristically coloured or it comes to the present colouring, since certain elements are represented in the stone, which actually do not belong to the crystal structure? Peculiarly coloured gemstones are summarised under the term idiochromatic, while foreign-coloured elements are called allochromatic. Basically, the colour of gemstones can be said to consist of three decisive components, namely the hue, the brightness and the colour saturation. The hue is the exact designation of the position of the gemstone colour in the colour circle, where shading and nuance are precisely described. Brightness is how dark or light the hue of the gemstone is, while saturation is how intense it is.
