Mirror with Jade Disk Inset, 475 BC-9 AD. Mirrors with a jade disk inset are perhaps the rarest of all known bronze mirrors in China. This object's conception was unquestionably aristocratic, and it was meticulously and exquisitely crafted. Aided by the skillful carving of its surface, the nephrite here exhibits a subtle luminosity. The disk features within the inner circle a pair of phoenixes and in the outer ring a set of four oxen masks having extended and interlocking horns-motifs often seen in jades of the late Warring States period and early Western Han dynasty. Consequently, this mirror has been dated to that span of time.