What's missing and what I would have done (spoilers)

The film needs a better wrap up scene explaining why Watson thought Bleeker was who he said he is, and why the diamond owner wasn't upset about her son's death.

If I was Holmes, I would have switched the diamond and then later announce I had switched it and bring out the "real" diamond but it's just a second fake. That draws out the villain without risking the real jewel.

"Worthington, we're being attacked by giant bats!"