Rainbow Dust ProGel are professional gel food colours are so highly concentrated that only need the smallest amount to give deep, rich colour to creations. Simply mix into your sugarpaste, marzipan, buttercream or batter and watch it transform into your desired colour. Rainbow Dust ProGel are professional gel food colours are so highly concentrated that only need the smallest amount to give deep, rich colour to creations. Simply mix into your sugarpaste, marzipan, buttercream or batter and watch it transform into your desired colour.