I make these rings in 1mm (18g) 1.2mm (16g) and 1.6mm (14g) with an inner diameter of 8mm, 10mm och 12mm.
In 18g the ring is a twist open ring where the ornament hangs of the ring. In 14g and 16g the ornament is a captive bead that "clicks" in.
The rings are made from pure niobium that I heat up to make it black. The ornament/lock is handcasted in bronze and given a slightly rough finish.