Carving shell?

This is completely random, but my research has led me no wheres so I thought why not:

I'm carving a heart out of a mother of pearl shell which I found in Bangladesh, which I'll put on a silver chain for my girl friend. At the moment, I'm only using one of those pretty lame carving knifes, like for art or for chopping up pencils; progress is slow and I have until Friday to complete the necklace.

I don't suppose anyone has any ideas or pointers to help me do this? Mh, it's a longshot.