You answered your own question.
My friend actually owns a financial company, With bad credit if you apply you will actually make your bad credit worse, because getting refused gets logged too.
Pay off your old bad debt before you get more credit. Put the item on layaway and pay it off over time.
It is doubtful a jewelry store would finance anything if you have bad credit. However, if you did a lay away
and paid towards it as often as you could, they would likely welcome your purchase.