In response to this and the other on this forum...Circle lenses would make your iris appear bigger b/c they tend to be a larger contact with a limbal ring (black ring around the contact). HOWEVER, these are not legally sold in the U.S., and because of that, prescription, quality, base curve size, etc, is not really monitored if you're just buying them online from any old international site. A contact that is not the right size for your eye can scratch it and damage it, causing infections and ulcers of the eye. These contacts also have a higher risk of doing that b/c they are larger and might slide around your eye. And, since they are not FDA approved or regulated, you never know if you're getting a good, clean pair of contacts. Not worth it!

Anyway, there are plenty of other colored contacts that tend to have a slightly large diameter with and without limbal rings that would give a larger iris effect. (Venus brand contacts, for instance).

Hope that helps =)