I've been thinking about a random subway tile stone look with glass accent backsplash for my kitchen. I happened to be on Arizona tile website and I found the coolest tool to do a mock up, I am having so much fun I thought I'd share the link. If your mockup doesn't look good just change the percentages or colors or grout color etc.

On the right handside of the home page under news, see create mosaic, click on that, wait for it to load, add your shape, colors and percentages, styles, grout and click create blend.

Here is a link that might be useful: Arizona Tile Mosaic Backsplash Mockup