I'm currently studying to become a hairdresser, doing an NVQ2 at college and I need help with understanding my new colour chart. We normally use Redken colourants but I want to expand my knowledge and have been told Wella Koleston is a good brand but I cannot get to grips with the numbers used Can someone explain to me the depth and tone numbers used is the Koleston range?? PLEASEEE!!?? I'm wanting to know things such as what colour-tones do the numbers stand for and what is classed as the 'natural' tone mixed with colous for grey coverage??