If you see no difference in the hair colour after using Caramel, this (as with some of the other Colour Restore shades) may be due to the fact that you have applied it to a base darker than the actual Caramel depth. Caramel is a base of 7.3, which is a medium, golden blonde. If someone who was brunette, or even a light brown applied Caramel they would not see a huge shade difference. The hair might look more golden, but the actual caramel colour would not be true to the box swatch. Caramel is designed for use on very light blonde bases or those with highlights, balayage and ombre who are seeking a more natural darker blonde. The purpose of my creating Caramel was to offer consumers an option to deepen lightened hair to a natural depth, whilst not actually becoming a clear brunette. Colour Restore Caramel is a soft lightest biscuit brown when applied to light bases and is a great option for people who are finding their hair is becoming too light and want to soften dark regrowth sitting against previously lightened hair.
Another factor to check is if you have clarified your hair prior to application. If the hair is coated with conditioner and styling product residue, it is impossible for Colour Restore shades to enter the hair. Therefore, if your hair is a light blonde (or lightened base), and you have seen no result, I recommend you use Precolour Clarifier and apply the shade again.