Well, funny you should say that lol.

There is another brilliant documentary on the Cheapside Hoard' It's called London's lost jewels.
I'd put up the link but I don't want to get into copyright trouble. You can find it on Youtube, it's presented by Shaun Leane.

In the documentary, he talks about how diamonds and emeralds would have got to London in the early 1600s but there is also a bit about how they manufactured fake jewels buy dyeing stones and passing them off as rare gems.