it's a type of material that's quite popular now for shalwars and stuff. it's kinda like a cross between chiffon and silk and it's preferred because it gives a nice fall and matches well with the look of chiffon outfits as opposed to using silk. it's most likely a synthetic fabric.
p.s the trousers in that above pic are in grip.
^ i thought there are two kinds of grip: synthetic & pure. i'm not sure, though...