"Security used in diamond mining is interesting. "

At at least one company that sorts diamonds, the Women who work there are rewquired to wear locking chastity belts on the job so they cannot steal diamond by putting them you know where. I got a picture actually if you want.

Even if they know the weight of it all before it comes in, and can of course see what comes out, the practice actually makes unnecessary certain invasive searches should a theft occur. Or actually any other reason the team might "Come up light".