I know some ladies bleach and sand theirs, but I don't treat mine at all. I use skinny ivory dominos, not the chunky white ones. I stamp on the flat side, not the dotted side, and I love to dress up the sides of it also, with microbeads, or ink. I usually stamp on them with stayz-on, and I have also stamped my image on a domino shaped piece of tissue paper, colored the image with pencils, and then applied it to the domino with crystal effects.
Have fun! I would love to see your results!