Moonstone
The sheen moves as the hand does, which is the entire argument for it. It cleaves, so it is bezel-set here and kept from hard knocks.
Hardness — 6 to 6.5 Care — protect from knocks; no ultrasonic Source — Sri Lanka, India
Moonstone
Feldspar with adularescence — a sheen that floats above the surface, made by light scattering between layers too thin to see.