Water Based Colours Want to add some colour to your reed diffusers? Try our water based colours. A few drops of our concentrated colour is all it should take to vibrantly colour your reed diffuser mixture. We recommend to always add our colours after you have added the fragrance. Fragrances can affect the finished colour of your reed diffuser. Please note the image provided shows an approximate colour once added to reed diffuser base. Colour will vary dependent on the fragrance used and the amount of colour added.