Colour code 4/6 means that it is a mixture of those two colours. If the colour code is 30/ 130-33 it means that there is an even mixture of colours 30 and 130 and a small amount of colour 33. Therefore, "/" means an even mix of the two colours and "-" means that a small amount of the colour is added. The colour quality may vary depending on your screen's resolution. Therefore, these colours are to be used only as a guide.