These facts are about stolen property law in Tennessee. Other states may have varying laws.
Several years ago, I represented a fellow who had a very unique banjo stolen. The banjo was located 20 years later at a music festival. The banjo was worth about $3,000. The maker had made only 201 banjos, and was deceased. His banjo's became very collectible in the old-time music world (not bluegrass).
The fellow that had the banjo refused to return it to the owner, despite tons of proof of ownership. He demanded the full value of the instrument. We later learned at trial that he claimed he only paid $125 for it at a yard sale.
We filed suit to order the banjo returned and eventually after an appeal, were successful in getting the banjo returned to the person from whom it was stolen.
The law in Tennessee is that the holder of stolen property has no greater rights than the thief, so the downstream holder/purchaser of the stolen property has no right whatsoever to the property. The thief had no legal ownership, so anyone to whom he sells the property has no legal ownership of the property either. The downstream purchaser is left with nothing but a legal claim against the person that sold him the stolen property.
The holder of the banjo in this instance, claimed he was a bona fide purchaser as he had no knowledge of the theft. Again, the law did not recognize this theory.
The story becomes very different if you take your cue in for repairs and the repairman sells it against your wishes. The act of voluntary surrendering the cue to the repairman changes everything. In that instance, the rightful owner is left with only a claim against the repairman for selling the cue. The downstream purchaser does become a bona fide purchaser and has good title to the cue. The rightful owner cannot, in Tennessee, bring a claim against the downstream holder of the cue for its return.
First order of business is to file a police report on the stolen cue. That at least establishes that it was stolen, that a report has been filed, and down the road, can be useful.
I play with a Southwest. My insurance company, Cincinnati, has photographs of the cue and has it insured for replacement value. Its not very much, about $100 per year. It won't get the cue back but at least gets you some money to replace the cue.