I had my knives insured on my renter's insurance policy a few years back.
The insurer was AMICA.
On a plane trip, I put several into an outside pocket in my checked luggage (dumbass thing to do). When the luggage came down the carousel, that outsied pocket was open and the contents gone. There was no way that the pocket would have opened by accident.
I filled out a police report. A number of small, expensive items were gone. Amoung them as an RJ Martin Kozuka, a Bud Nealy damascus Aikuchi, and a few other nice ones.
When I called Amica, they couldn't believe that a knife cost that much (and as customs go, these were not much--maybe a total of $900 worth of knives).
I called Bud and RJ and they FAXED me:
affidavits that they had sold me knives.
replacemant value of said knives.
Once I got the info to AMICA, I received the check minus my deductable.
So this can be done with regular insurance companies. However, coverage is more extensive, and more hassle-free, with Collectables.