Fine jewelry is defined by what it is made of, and by that standard, gold over silver qualifies, with genuine precious metal at both the base and the surface.
A Storied Heritage
Jade's association with divine authority across ancient China and pre-Columbian Mesoamerica (burial goods, ritual objects, regalia in both contexts, without any connection between the civilizations) is a cross-cultural convergence with no equivalent in the history of any other gemstone material.
Visually Speaking
Whether it's diamond-set, gemstone-set, or engraved, the flat housing surface of a box clasp makes decorative work possible. In this way, an otherwise plain closing mechanism is transformed into a decorative detail that contributes to the piece overall.