User blog:Blueeighthnote/Colors/Colours

Certainly, the number of colours in a level can affect difficulty of a level. Another factor would be the size of the area. Size will affect the number of matches available and oppurtunities for making special candies.

The 6 colours are  Red , Orange, Yellow ,  Green ,  Blue , and  Purple.

For some reason, iOS and Andriod versions decided to have different colours than those on Facebook. This causes a lot of confusion. Several comments on Youtube are filled with people saying, "There's no Yellow in yours!", while there are clearly the same number of colours both on Facebook and other devices.

So, I think I will clear this up: Currently, only Level 31 has 3 colours, while Levels 15,16,18,24,34,55,69,73,74,77 etc. have 4 colours. The majority of other levels have 5 or 6 colours.