The jewelry most commonly worn in a navel piercing is a curved barbell. Curved barbells unscrew into three pieces: the bar itself and the two beads. Another jewelry option that works well for a healed belly button piercing is a captive bead ring, a continuous ring that holds a ball in place between the two prongs. Bars and rings can be purchased in a variety of colors and styles, both from your favorite piercing shop and online.
Sketch an image of the jewelry you want. First, decide whether you want a bar or a ring. The shape of your jewelry determines the kind of bead you'll need to buy. A sketch can help your piercing shop put together the closest match to what you imagine.
Measure your current barbell or ring to determine the length you need. Piercers usually insert a longer bar than necessary into a new piercing to allow room for swelling. When your piercing is healed, you can change to a shorter bar for a snug fit. Measure your current bar with a ruler, excluding the beads. The most common size for an initial piercing is a 14 gauge, 7/16 inch (11 mm) curved barbell. You may wish to go down to a 3/8 inch (9 to 10 mm) bar when your piercing is healed. Measure a ring across its diameter, from inside to inside. Do not include the thickness of the ring in the measurement. The gauge will remain the same.
Visit a piercing shop to choose your material. Rings and curved barbells are most frequently made of surgical stainless steel, but you can also purchase them in yellow, white or rose gold. Another metal option is titanium, which comes in lots of different colors. You can also choose Tygon, a plastic surgical tubing, if you want a flexible barbell. Beads can be screwed into Tygon just like they can into metal. Your piercer can help you choose the best material for the design you've sketched.
Look through the catalogs your piercing shop receives from their jewelry suppliers. If you don't see exactly what you want in the store, your piercer will usually be happy to order it for you.
Ask your piercer to clean your new jewelry in the ultrasonic machine and autoclave upon receipt. Even though the jewelry has never been worn, it will have gone through several people's hands before it gets to you. Autoclaving sterilizes the jewelry to remove all viable microorganisms from its surface, making it safe to insert into your body.