For blueish purple I use mineral oil, rubbing alcohol and fresh blueberries smushed up into juice, screen it so you don't have chunks in it, the oil is for making it stick and the alcohol for fast drying and the berries well you can figure that one out. I don't have a set measurement I just mix it together and and try it on a piece of wood like the one I want to put it on. I hate painting wood but I don't mind doing it the natural way. I just finished a piece and I used cranberries and blackberries together came out kind of maroon which was ok as it was a wine holder. Give it a try and see if you like it.