For anyone who doesn’t know, this is a ball captive ring (also called a BCR or captive bead ring.)
These items consist of two parts: the ring with a small opening, and the ball, bead, or decoration that fits into that opening. The opening allows the ring to be easily placed through a variety of piercings, and then the ball (which is held in by small divots in its sides) closes off the opening to keep the item secure.
Ball Captive Rings are most commonly composed of a ring made of metal (surgical grade stainless steel, sterling silver, 14 kt gold, titanium), and a ball made of either similar materials, Austrian crystal, acrylic, or natural stone. They can have standard spherical shape, other shapes like hearts, stars, and triangles, or include dangling pieces.
The captive ring is a maverick piece of jewelry, wearable in nearly any piercing. Some piercings they are commonly worn in include lip piercings, like snake bites, angel bites, and spider bites), labret piercings, septum piercings, nostril piercings, eyebrow piercings, many piercings of the ear incuding lobe piercings, orbitals, rooks, daiths, tragus, anti-tragus, helix, and conch, belly piercings, nipple piercings, and surface piercings such as Madisons and corset piercings.
Captive bead rings are easy to match and coordinate in multiple piercings, and make the perfect addition to any jewelry wardrobe.