I am wanting to color white chocolate disks to put into a chocolate mold...is this possible.

I was thinking of using a black gel color to get gray?

You can color the white chocolate candy melt discs but you need to use the colors made specifically for candy (else your chocolate may sieze up)..

I also just read this post a few minutes ago where a CCer points out Americolor has an oil that allows you to use regular gel pastes for chocolate:

http://www.cakecentral.com/cake-decorating-ftopict-486883-.html

Yes - a little black will make it gray.

You can add the icing colors to crisco and then add that to the candy melts.

I used about 1/2 to 1 teaspoon. I think I used a 1/2 package of candy melts.