Check with your agent. Most homeowners policies will cover listed personal property away from your home, ie some breaks in to your motel room and steals your cue or jewelry or ever if you just loose it or whatever. If it is very expensive you may have to purchase a "ryder" listing and describing the property to be covered it's value. The other option is to require the gallery owner to cover it under his business liability policy.
As long as it cannot be associated with your work, I believe a rider would be just fine. Some companies have serious issues with things like that. Most pro photographers have separate insurance because of this, and the fact that it is nice to hold 1 million in liability if you drop a light on someones head.
Always best to talk to your agent, get in in writing, and make damn sure the insurance company didn't put in a loophole.