I have seen it done without tile to seperate the two colors and it looked fine however it was on a shelf where a sandy beach color was used on the beach entry and then when it transitioned into a baja shelf the rest of the pool was in tahoe blue. This looked fine. We also considered doing the same thing with our beach entry/shelf and the pebble company could do it but they would have charged an extra $600 to do it. In the end we just decided against it and went with one color.

So technically it's possible however if your applicator is uncomfortable doing it or has never done it before then I would definately pass on having them give a try on your new pool.