Here's the link to one of the insurance brokers, my friend who started her jewellery business not so long ago was in touch with these guys, not sure if she took the insurance from them but she got a lot of help. so I'm guessing its worth getting in touch directly and see if they can help you, if they can't they'll put you intouch with someone else who can.

** It won't let me put the link here sorry, look for thmarch co uk / business / insurance - for - jewellers /

Thank you