That's the back of the coaster...forgot to take a picture before I started painting. You can see that it was just a basic, light-colored wood.
I painted 2 coats of light pink to serve as primer and undercoat. It was really pretty and I almost left it right there but I had another idea in mind.
Since I'm new to this painting world, however, I do have a question. If I'm going to use it as a coaster, would it be best to paint some sort of clear coat on top to keep out moisture? Is there even such a thing?