By p. Pearl in your headline, I think you mean Poulsen's Pearl?

Assuming that, I think that black iris would look GOOD. I have both Dainty Bess and Poulsen's Pearl and I can envision that combo. Are your black irises deep, deep royal purple or are they a deep, deep burgundy? I love the combo of blackish flowers with light pink whichever black they are (although, my favorite combo with the deep burgundy is apricot-colored roses). But, I do believe that the lighter pink of either of those roses as a backdrop would make the black irises stand out very nicely.

Annabeth