Beautiful work by Van Cleef & Arpels.
The mystery setting is a technique developed by Van Cleef & Arpels for mounting precious stones without any of the setting claws showing. All trace of metal completely disappears from view and we are left with just the jewels. Thus one has the impression that the stones are free, their glare is magnified and they shimmer like cat’s eyes. In order to apply this jeweler’s technique to the REB-5 Tourbillon, the watch case had to be rebuilt to allow for the “invisible” setting of the stones, which were cut with extreme precision and set using minimum tolerance levels. And to ensure all traces of the diamond settings were well and truly hidden the setters worked under microscopes, very much like micro-surgeons. – From Watch Luxus