I cannot take credit for this card, as it was sent to me as a sample from Elizabeth Crafts Glitter. However, it does show how you can successfully color glitter with Copic markers. As you know, Copics are alcohol based, which means that they will dry on non-porous surfaces (which includes glitter). In this case, they started with the clear "highlites" glitter. All of the color is from the markers. Now, there are a couple things you need to pay attention to. The glitter can get into your marker tip - you want to use GENTLE pressure with the markers to reduce this as much as possible. You should be able to get the glitter off by running the tip on a piece of paper. Worst case, you can always replace the tip.
Just ANOTHER use for your Copics!
Jeannette