Ah, okay, this adds some clarity (pun intended). I don't know much about the Insurance market down in Florida as far as recommending someone specific. If you haven't already done so, you may want to check with Allstate, American Family Insurance, (you already said State Farm was a no go) Country Companies, Progressive, Geico, Prudential... Those are a few that come to mind. Progressive and Geico (a Warren Buffet company) are more Internet based than the others, but all should be available online.
I am also assuming you asked your current agent if they can recommend anyone that can insure jewelery without you having to have homeowners with them? If they don't know anyone, call some of the better known jewelers inquiring as they may have a name or two, as would some banks potentially. Your mortgage banker or real estate agent would be some other good sources to inquire for names/contacts. Also, try some of the large investment brokerage firms either to see if they do it or know someone... Merrill Lynch, Morgan Stanley, Smith Barney to name a few...
Finally, I wouldn't say where you bought the jewelery from (unless they force it)... It shouldn't matter really. Get an independent appraisal (may cost you $50 to $150 depending on who does it) and that is all that should matter. Where you bought it should be irrelevant.
Good luck. I'd be curious to know what you find.