Last I checked, HO Policy provides limited coverage for many things. Guns, stereo equip., jewelry . . .
"What you are looking for is an Inland Marine rider to your homeowner's policy. This should be an all risk policy with no geographical restrictions -- in other words: all risks/all over the world. If you have problems, I would suggest an independent agent who has the ability to write for a variety of companies. My opinion, based on experience, is that Nationwide,
et al., is not who you want to be dealing with. However, there should be at least one insurance cat on AZB who can give you chapter and verse."
Value is stipulated when coverage is written -- you have to supply evidence of value at outset. They have to pay upon proof of loss. I had damaged guns that were a total loss from salt water. They paid the stipulated value quickly -- they cannot adjust a total loss on this type of policy. Might have taken longer if the guns had washed to sea.
See,
https://forums.azbilliards.com/threads/insurance-for-my-cues.537603/#post-7119013
Do us all a favor and learn to use the Search function.