Tw25: You didn't ask, but..... I'm going to tell you the problem I had finding a blue tile to go with the glass tile I wanted. I worked on that for weeks, even getting others on TFP to vote for their favorite. Our pool designer had told me from the beginning to go with a neutral or beige waterline tile, but I wouldn't let go of using blue waterline tile. I couldn't find a blue tile that complemented the glass tile or didn't out-do it.
When appelbe posted his pool build, I knew I loved it. Finally, it hit me that his lovely beige tile was the perfect answer (to me) to work with and show off his glass tile. Once I let go of the blue tile idea, I made my decisions in one day for all my tile/stone. Now, I love the beige waterline tile on our pool, especially with the coping. (you can click on my pool build link in my signature)
So think about using a tile for the waterline that goes with your coping/decking. Then there is no conflict between the glass tile and waterline tile. If you want more color, maybe there are steps elsewhere in the pool where you can trim with the glass tile.
I'm not saying you won't find the perfect blue waterline tile to go with whatever glass tile you choose. But if you get stuck like I did, try a more neutral waterline tile.
What helped me decide on which glass tile was setting it outside in the sunlight on the edge of our pool. I left it out there for days and looked at it from the back windows during all different times of the day, sunny and cloudy. That helped me more than a brief look outside. Hope this helps. Take care. Suz.