I've just come across a supplier of custom printed jewelry tags and earring cards, for jewelry artists who prefer to order them ready-made instead of making their own.

Custom printed earring cards
by Dolphin Bead Designs

They also have jewelry tags in several shapes, complete with a plastic fastener for attaching the tags to your jewelry, and some unusual types of jewelry cards - including ones designed for hairbows, rings, pendants, pins, and wine charms.

Custom printed folding jewelry tags
by Dolphin Bead Designs

Dolphin Bead Designs has a selection of fonts and graphics for their printed tags, and offers sampler packs of preprinted or custom printed cards, so you can see what you'd get before you actually place an order.

See Jewelry Hang Tags and Earring Cards for tips on designing and creating your own jewelry cards.