Sterling silver with one brass ball bearing as an added kinetic element. This ring was a custom order by a doctor's wife who wanted that her husband had a secure place to keep his ring, when he went into surgery and had to scrub in.
Nurnberg diptych sundial from capable of operating between 42 and 54 degrees of latitude. The brass insert is a mystery: Possibly an annalematic sundial to allow orientation without compass. Currently in Louvre.