Light and the way the light falls on a specific area influences the colour that you see. For example, a grey colour in one area will appear grey, and the same colour in a different room or outside area that has more or less light, could appear to be more blue than grey. It is always advisable to first purchase a sample of the colour you are looking for and paint a small piece of that sample in the room or exterior area that you would like to paint it. This will give you an indication of how the colour will appear in that light.