I was actually wondering if I have an encrusting gorgonian instead of GSP, but I used Eric Borneman's "Aquarium Corals" to closely compare the polyps on my GSP to the ones in the photos. My GSP's polyps don't look like HBtank's which have smooth "tentacles". Mine look like the bottom left photo on page 120 of the above book, as well as the bottom photo on page 119 if you happen to have that book.
My photography sucks (or maybe the camera isn't suited), so the color is not as good as it is in person. The mat is definately purple, no brown tint to it at all it's just not as vividly purple as I usually see. It's more of a white tint that mine has...looks faded. The polyps are "fringed" (like the above mentioned photos) and they look like they are brown and fluorescent green was painted on. Haha! How's that for an odd description? I'll see if I can get a better photo...