I used to work as a property claims adjuster for a large insurance company. It's the worst possible job in the world that does not involve slaughtering animals or working naked in sewage pipes.
There are two insurers that specialize in high society clients, and would offer the best coverage for collectible items. I did not work for either of these companies, so no loyalty BS here, just straight dope.
Fundamental Insurance Brokers
Chubb
I directly linked to the info you are looking for, but read on for some details.
Not only does your homeowner's or renter's policy not cover your pool cue collection past the limit of coverage for personal property (which can be limited even further by limitations clauses in the policy), but it only covers your personal property from loss due to specified perils. So if one of your cues were to simply fall over and break, it would not be covered at all.
Homeowner's policies have three types of coverage; Coverage A (your physical home, garage, fences, sheds, etc.), Coverage B (your personal property, i.e. stuff not nailed down), and Coverage C (liability coverage for when your friend comes by, gets drunk, and breaks his neck while attempting to puke on your sofa). Forget Coverage C for this argument.
Coverage A COVERS your home UNLESS the cause of loss is EXCLUDED.
Coverage B COVERS your personal property ONLY if the property is damaged by a SELECT SET OF PERILS. This is an important distinction.
Damage to your home is covered unless it is caused by Flood, Volcano, War, Acts or Decisions of government authorities, etc. i.e. the exclusions.
Damage to your personal property is only covered if the damage is caused by certain events, such as fire, windstorm or hail, etc. Cue fell over and broke, sorry. Cue was eaten by moths, sorry. Cue got moldy in storage, sorry. There are many many scenarios in which your cues would not be covered. On top of that, your policy probably deals with replacement cost in a manner which will piss you off. Generally they pay you "actual cash value" up front, and replacement cost only if the item is replaced with an item of "like kind and quality". Depending of the insurer, or the adjuster who's mother just died, like kind and quality and actual cash value can mean many things. There is also a time limitation of one year for replacing the item. Try and get a Searing etc. within one year!
The only problem you are going to have is valuing the cues. Most special policies of the type I linked to above require independent appraisal. This costs money, and the insurer has the right to not accept the appraisal (before selling you the policy, after it's sold they are stuck).
I would contact an agent for each of those companies, see how they would go about valuing your stuff, how much the coverage costs, and decide based on that. Also, your current insurance company probably offers special riders to your homeowner's policy that cover these types of items in the same way, but be careful, policy language rules, and your agent generally has NO CLUE about claims handling.
Good luck.
