Marianne Walker from Copic has started a very informative blog telling you everything about Copics. Her discussion today was about paper and Copics. My paper of choice has been Curious Cryogen White which I get from Cutcardstock . I love the shimmer of the paper even through the inks. But I also have some PaperTrey Select White that works nicely as well. As you can see from the scan, the Cryogen on the right is not a true white paper and because of this your colors will be a little deeper. In my opinion, the Cryogen blends better with less ink. But I have found that ink does tend to bleed easier on the Cryogen so you want to have a light hand. I felt I got nicer blending on the Cryogen with less ink than on the Select White.
This next picture is a closeup taken under a bright halogen light, you can actually see the shimmer of the Cryogen paper. In real life, you would have to tip the paper in the light to see the shimmer. It is a very nice effect. But you can also see that the line between the lighter and darker inks is smoother on the Cryogen on the right than the Select White on the left.
Both examples were stamped with Tsukineko Memento Tuxedo Black ink, no heat setting required.