WHAT IS A BASE COLOUR?
The first number which appears on the colour chart is the base colour. This number indicates the base level of the shade you would like to achieve. It shows how light or dark the colour is
WHAT ARE THE TONES?
Next we will look at the second and third numbers on the colour chart that appear after the decimal point. These numbers indicate the primary and secondary reflects/tones that are present in the colour. The position of the number determines the final colour with the first number after the decimal point being the strongest tone and the second number after the decimal point being more subtle or softer.
6.43 = 6 (blonde) . 4 (copper) 3 (gold) which makes this colour blonde with copper and a small amount of gold.
If we reverse the numbers to
7.34 = 7 (blonde) .3 (gold) 4 (copper) which will be blonde with gold and small amount of copper.
There are also 0's in our numbering system and they have a different meaning. A zero after the decimal point means there is no primary (or predominant tone) in the colour. A zero in the secondary colour position actually means the primary tone is intensified.
Some examples of this:
6.04 = 6 (dark blonde) . 0 (no primary tone) 4 (copper) so the colour will be dark blonde with a small amount of copper.
6.40 = 6 (dark blonde) . 4 (copper) 0 (intensify). This colour will be dark blonde copper, copper, copper (or intensified copper) this could be written as 6.444 instead but we limit the length of the number written on the tube.