Glass tiles for the backsplash should look good. Keep them simple without a lot of contrast in color......You could do soft shades of grey, beige and green. Or you could do a green and beige combo......There are a variety of options.

Bring home samples, tape them up against the wall of the back splash and look at them for a few weeks. The choice should become obvious soon......

Do you have pictures of the kitchen? Take pics of the kitchen with you when shopping and bring home samples. I would stick with the same family in color, or a neutral to have the focus on the granite. Ensure you stay with the flow of the room.