Depends on how much the piece was appraised and insured for, the deductible with your insurance and how much your insurance will increase when you file a claim. As the hypothetical question to your agent......THEN, decide if it is worth it to file the claim.
Personally, I have my diamond, watch and earrings covered and it costs me about $1000 extra a year. They are the only pieces I ever wear, I have a specific place they go if they are not on my body so if I wasn't wearing it, it wasn't in the one place where it's stored, then I would look at filing a claim. Unless it is a no brainer and someone hit me over the head in the parking lot or something and took it... then yes, file the claim and I'd be glad I came out of it alive.
Best wishes and I hope it you end up finding it.