Reversible joint for fastening costume jewellery elements, jewellery elements or the like comprising: - a first section, connected or connectable to a first end portion of a costume jewellery element, said first section comprising a connecting pin having a main body, a rounded and/or longitudinally concave head and a convex segment defined between said head and said main body, said head having a cross-sectional diameter larger than a minimum cross-sectional diameter of said convex segment; and - a second section, connected or connectable to a second end portion of a costume jewellery element, said second section comprising an engagement seat adapted to house said connecting pin and comprising an elastic bearing 40 having an inner pass-through cavity; wherein said first section and said second section may be reversibly connected by introducing said pin into said bearing, said pin being held in position within said bearing by mechanical interference; characterised in that: - said cross-sectional diameter of said head and a cross-sectional diameter of a minimum section of said pass-through cavity have a dimensional ratio ranging from 1.25 to 1.5 with a tolerance of 5%; - said cross-sectional diameter of a minimum section of said convex segment and the cross-sectional diameter of a minimum section of said inner pass-through cavity have a dimension ratio ranging from 0.9 to 1.25 with a tolerance of 5%; and - said inner pass-through cavity has an inlet portion and an outlet portion, wherein a diameter of said outlet portion is smaller than a diameter of said inlet portion, and wherein while introducing said head within said bearing, at least said outlet portion is elastically deformable. - a first section, connected or connectable to a first end portion of a costume jewellery element, said first section comprising a connecting pin having a main body, a rounded and/or longitudinally concave head and a convex segment defined between said head and said main body, said head having a cross-sectional diameter larger than a minimum cross-sectional diameter of said convex segment; and - a second section, connected or connectable to a second end portion of a costume jewellery element, said second section comprising an engagement seat adapted to house said connecting pin and comprising an elastic bearing 40 having an inner pass-through cavity; wherein said first section and said second section may be reversibly connected by introducing said pin into said bearing, said pin being held in position within said bearing by mechanical interference; characterised in that: - said cross-sectional diameter of said head and a cross-sectional diameter of a minimum section of said pass-through cavity have a dimensional ratio ranging from 1.25 to 1.5 with a tolerance of 5%; - said cross-sectional diameter of a minimum section of said convex segment and the cross-sectional diameter of a minimum section of said inner pass-through cavity have a dimension ratio ranging from 0.9 to 1.25 with a tolerance of 5%; and - said inner pass-through cavity has an inlet portion and an outlet portion, wherein a diameter of said outlet portion is smaller than a diameter of said inlet portion, and wherein while introducing said head within said bearing, at least said outlet portion is elastically deformable. - said cross-sectional diameter of said head and a cross-sectional diameter of a minimum section of said pass-through cavity have a dimensional ratio ranging from 1.25 to 1.5 with a tolerance of 5%; - said cross-sectional diameter of a minimum section of said convex segment and the cross-sectional diameter of a minimum section of said inner pass-through cavity have a dimension ratio ranging from 0.9 to 1.25 with a tolerance of 5%; and - said inner pass-through cavity has an inlet portion and an outlet portion, wherein a diameter of said outlet portion is smaller than a diameter of said inlet portion, and wherein while introducing said head within said bearing, at least said outlet portion is elastically deformable.