Cartier Kara

The bracelet in the image is called a Juste un Clou bracelet, which is French for "Just a Nail". It was designed by Aldo Cipullo for Cartier in the 1970s. The design is based on a common nail, and the bracelet is made of gold or silver with a diamond set at the head. The bracelet in the image is black, which is achieved through plating, and it is unclear from the image whether the stone is a diamond or cubic zirconia.

The Juste un Clou bracelet is a popular choice for both men and women. It is a stylish and edgy piece that can be dressed up or down. The black color of the bracelet in the image gives it a more modern look.