This morning I answered this question with this answer. The question's timestamp is 14:17:36Z, and my answer's is 14:22:20Z. Unless I'm bad at math, this is within 5 minutes, and should earn the Perfect Topaz gem, but I haven't been awarded it.
Unless "answer a question within 5 minutes of it being asked" also requires being the accepted answer, in which case the description should be clarified.
I just answered another question and was immediately given the gem for it. As a result, I'm assuming that the problem is actually a bug with whatever's checking the time. I've changed the tags accordingly