Abstract: A piece of jewelry is disclosed, which has an adjustable inner diameter, includes first and second parts, in the form of portions of a ring and having respective first and second ends, the first and second parts being connected to each other by a pivot type connection. Moreover, each of the first and second parts has a first of its ends adapted to cooperate with a first end of the other part, by nesting of variable depth, to define a closed ring of adjustable inner diameter. At least one spring member is adapted to act on both parts so that their first ends tend to nest one within the other to reduce the inner diameter of the piece of jewelry. The pivot type connection is at a distance from the second end of the first part, the latter having an overlap portion, located between the pivot type connection and the second end, of greater radius than an inner portion of the second part facing which it is located, so as partly to overlap it.