Mother-of-pearl's iridescence is permanent because it's structural. The microscopic aragonite layers in the nacre create light interference patterns called orient, and those patterns change as the viewing angle changes.
Industry Insight
A natural pearl forms entirely without human intervention when an irritant enters a mollusk and is coated with nacre over time. A cultured pearl results from deliberate nucleus implantation. Both consist of genuine nacre, and the distinction lies entirely in how the process began, not in what the pearl is made of.
A Storied Heritage
Fine jewelry's move toward cleaner surfaces in the latter half of the twentieth century created the conditions for the concealed bail to become standard. When the design language shifted away from visible hardware, the attachment point became something to solve for rather than display.