Fine necklace in redgold set with three fancy coloured diamonds
The colour of a coloured gemstone is judged differently from the one of a colourless diamond. In diamonds, the discerning eye will make out small nuances that may greatly influence the value of the gem. The less colour is visible in the diamond, the more valuable it is. This, of course, does not hold true for so-called fancy diamonds, which come in various colours and are highly sought-after. Along with the colour, which is graded from D to Z in colourless diamonds, the fluorescence displayed by a gem can also negatively influence the value of the diamond.
In coloured gemstones, on the other hand, colours are, well, welcome. The hue, saturation and tone of the colour, are judged and may influence the value of the gem greatly. Even fluorescence, unwanted in diamonds, may have a positive influence on the gem’s value. There are certain colour terms sometimes given out by gemmological laboratories that are highly coveted by the trade beyond the normal colour denominations. Among them is the “pigeon blood red” colour for rubies as well as “royal blue” and “padparadscha” for sapphires.