Xisto is Portuguese for schist. It is stone that has been under pressure long enough to organise itself into sheets, and it splits along those sheets. That is why the villages of central Portugal are built from it. You do not cut xisto so much as persuade it.
The walls go up in flat, uneven courses, each stone sitting where the one below will take it. Nobody designed those walls. They are the record of a material being honest about how it fails. In the Serra da Lousã those villages stood empty from the 1960s, and the regeneration there sets new work inside the standing ruins.
The ring stacks the same way. Plates, offset, each resting on the last, the line where they meet doing the work rather than the stone.
Inspired by Kengo Kuma and Associates' Silveira Tech Regeneration Village, Lousã, Portugal. Solid sterling silver 925 with rhodium plating.