Navel piercings may be the most commonly performed body piercing below the neck -- in fact, they're possibly only second to earlobe piercings in popularity. As it happens, they are also one of the trickiest to place and hardest to heal. One key to belly-button piercing success is to choose the right kind of jewelry for the initial placement. The metal must be smooth and hypoallergenic, so as to minimize irritation and adverse reactions.

Surgical-grade stainless steel is the go-to option for most initial body piercings, including navel piercings. It's inexpensive and highly durable. Its one disadvantage is that it's relatively heavy compared to other choices. Make sure that your piercer is using true implant-designation steel alloys, as some stainless-steel body jewelry is made of inferior material that could cause irritation or delay healing.

Gold jewelry is another possibility for an initial navel piercing. The gold should be between 14 and 18 carats; any higher is too soft for use. It should also be made of a nickel-free alloy; make sure your piercer is reputable and knows her sources. Gold's greatest disadvantage is its expense.

Titanium is light and strong and routinely used for medical implants, so it makes a fine choice for body jewelry. Niobium is a metal similar to titanium and has similar advantages -- it's durable, lightweight and affordable. One unique aspect of both niobium and titanium is that they can be heat-treated, or anodized, to produce different colors -- you can have a pink, purple, green or blue navel ring as you choose. These colors may not last long, however -- especially if there's a lot of friction against the ring.