[Yes, a very interesting visitor. Such were those that ended up at 221B Baker Street. Though usually not at Christmastime. At the mention of a magic goose, Sherlock does give the man a look and shake of the head.]

I hardly think so. It was found in it's crop and I am inclined to think someone had put it there.

[After a moment, he tosses the gem to the other man to see, one if he catches it with any sort of reflex Sherlock suspects the man has, and two so he might see the precious stone for himself.]