I don't have this SU stamp either, but lucky for me I went to an SU card buffet and afterwards we could make cards with some of the demo's Christmas stamps. I fell in love with a lot of the stamps, this one included! I just may have to order it!
It's called Christmas Star, and is a single stamp. I stamped it with cherry cobbler ink and cut it out. I have seen so many cards with the star scored to look 3D, so I tried it out.
I love the look!
You can see it better on this photo:
I used the Seasons of style DP and the sentiment form Joyful Christmas to finish the card!