This should show a little underneath the unbuttoned high collar of the jacket. Snape uses a polished black wand. It has a few inches of carvings on the helm, but the rest is smooth to the tip.

(Not to mention: Voldemort falsely believed Snape to be the master of the Elder Wand, so he wouldn’t have fired such a spell in fear it would rebound.) In an excerpt from Rickman’s diary dated ...