I assumed you were referring to kitchen counter tops using concrete top and tiles?

1. For edge finishing, you can opt for the traditional way - a slightly rounded edge.
The key tip is to use homogeneous tiles. This way, the countertop will maintain a consistent colour tone throughout, when your tiler trims the tile edge to create a half-round finish.

Sample effect:


2. Alternatively, you can opt for 45-degree aka mitre edge cut on tiles to achieve a seamless edging. But to achieve a perfect mitre edge is not easy, hard to get local sifu who will be able to do it.
Local practice, usually only able to achieve a bird-beak effect.

Seamless 45-degree edging:


bird beak: