I have one hard, fast rule for all of the games I play and for all of the dice; don't make practice rolls!
For RM, I use the first pair of die I ever bought solely for RM. Since RM was the first game I ever started playing, those dice stay with that game and I've had fantastic luck with them. They are charcoal and peach. Charcoal is always the 10's. (They're grey and sort of orange-ish/pink-ish, but charcoal and peach sounds more worldly.)
After that first pair of die, I went on a die-collecting-spree and I have a good sized collection. I needed a bunch of 10's for the World of Darkness and Vampire games but those dice never cross over to RM. Sacrilege!
I have a handful of dice sets for D&D, one set which is absolutely cursed, but I try them anyway, every session, and the GM just laughs at me until I switch and then he just shakes his head because I prove yet again that the dice are cursed. The D&D dice sets NEVER see RM gaming time. In fact, they aren't even stored in the same gaming bags. I have a duffle bag for D&D since I don't GM that system ever and one large duffle bag my entire RM collection. No cross-contamination. I can't have the cursed dice infecting the good dice.
And it's not superstition if you can prove it.