All households must have insurance through that household policy, jewellery is covered as a possession up to a certain value the same your TV and stereo would be.
However without a jewellery article floater in your policy you can not be insured for the total amount of high-end pieces.  If you only have 2000 worth of jewellery you don’t need a specific jewellery article floater policy…
However, if you have 40K worth then you most certainly need a separate policy for your high-end items. In which case, you’d need a certified appraisal from a reputable (insurance accepted) document with current value, date, and address, and name to be properly insured.