It's a shiny, thick, latex-like substance. Usually black, tho I've seen gray used in rehearsal studios. Has a definite shine to it but the reflections are blurry. Surface has two notable features (besides the tape joins); scuff marks, which are duller than the rest of the finish, and ripples. Very water-like, really. It bunches and ripples under stress. You can actually see little stress patterns around the dancer's feet in at least one of the photographs you linked. And the whole surface undulates gently; it never quite gets all the way flat. Imagine taking a latex dress and smoothing it out on a hard counter-top; some ripples will still be there, especially around the seams. I'm thinking a really good texture would be such a deep stack of nodes might be simpler to paint it...displacement or bump map for the ripples, a specularity or reflectivity map for the scuff marks. And a little noise in the "black" as well (it does get dirty and less than thoroughly black). (Odd bit of marly trivia; often when mopped before performance they mix in a little diet coke. Helps the dancers get traction). As for light, light what looks good. I like to think back story a bit; what kind of space is this, what can they afford, etc. Be a difference between a small school and a big-city ballet. In a world of infinite number of lights and the ability to hang them anywhere (without regard to entrances or sightlines) I'd love to be able to light diagonals for dance. So much choreography hits those diagonals, but you really can't lay a light down that same angle, or isolate that moment properly. But I don't think that would be that believable in 3d.