We are a couple in Thailand that are getting a pool built these days. Its an in-ground pool 12x6 meter, and we are very excited about getting it. We have been reading the pool school and learning a lot. One thing that is a little confusing is that it says pool surfaces are 3 kinds, plaster, vinyl or fiberglass. We have selected tile from a big tile collection. These look like ceramic tiles. What category would this fit under, is it plaster?