Kotomi Yamamura shares this easy jewelry display to make from heavy cardstock, for showing necklaces or bracelets.
She uses this paper pattern to cut out her cardstock; the center line measures 23 cm (9.05″):
Once her cardstock is cut out, she curves it into a cone shape and staples the two flat edges together.
You can see a small tab she added to the display for looping the back of her necklace around so it wouldn’t slide off the display:
She suggests that since her jewelry tends to be large, you may want to adjust the size of the pattern to suit the size of your jewelry.