To schedule jewelry on your HOMEOWNERS POLICY, contact your agent. (I hope you aren't considering adding the piece you aleady lost. tsk tsk. That would be a no-no. LOL)
You will need to provide proof of ownership (receipt....showing description, date of purchase, & value). Sometimes it can be added without receipt -- but you still need that info. Pieces over $3000 require an appraisal done within the last 3 yrs.
Of course, all of the above is from the carriers we offer. Ask yours. It's about $12.50 per $1000 to schedule jewelry.
Also, if somethings not scheduled, mysterious disappearance isn't covered. AND theft is only covered up to $1000 TOTAL if pieces aren't scheduled.