Check here for a couple of color reference tools that are very helpful for your enameling projects.
One, is a product made for films in photography. It is very simple to over lay the sheets and see how the color changes. I had an inquiry the other day on how an enamelist could darker the red that they had available. It is great to be able to keep moving when you are in the middle of an enameling project.
I can be a bit hard to tell here, the red over the blue darkens the red.
Cool little color reference tool for enameling.
Enameling Polishing Tools