If you try to make this coloured sugar, one thing is guaranteed, the child in you will have a great time. Every so often you see recipes that call for sanding sugar, which is nothing but coloured coarse granulated sugar. The larger the granules, the better the results as it holds up better through baking. If the child within you is not quite satisfied with the colours of the rainbow, adding some glitter is always an option.
100g granulated sugar
2-3 tbsp vodka or gin
few drops water based food colouring of your choice
Mix the vodka or gin with the food colouring until the colour is evenly distributed and pour it over the sugar, to wet it. Mix it thoroughly with the end of a teaspoon, then spread it out on a try covered with grease-proof paper. Stir it occasionally, and leave until the sugar is completely dry. Store it in an airtight container. I used 300g of sugar and 6 tbsp gin to get 6 different colours. Work it out yourself, all depends how much you will need for you next baking adventure.
Recipe adapted from Mastering the art of chocolate