The suggestions I've seen here are correct

1st...smell your dice. If they smell of vinegar, they are beyond help . Keep them away from other old dice, I don't think (but I'm not positive) they will cause other dice to deteriorate...but they could speed up any deterioration that has started.

If they have started to crystallize, and do NOT smell of vinegar, give them a coat of clear nail polish (dab gently over logos, do not stroke the polish. Paint one side at a time, let it dry for several hours or overnight before doing another side)

A cool, dark place is best to store them

Thanks for the pictures you've been posting...I've enjoyed them