Catalogue entry no. 513a by Max Loehr:
513 Pair of Decorated Plaques
Translucent pale green jade with cream-colored spots (a), while the front surface of the other piece (b) is entirely calcified and cream-colored. The rectangular slabs are slightly convex on the decorated side and plain at the back. On each, two curly projections near the top are surmounted by a relatively broad part with a rounded contour. A short and narrow shank with a beveled back sites on top. The décor consists of an animal mask at the base, executed in low relief, and of incised, interlocked spirals above the mask. On the back a deep groove cuts lengthwise through the shank and adjoining part, while a deep and narrow arc runs from shoulder to shoulder. The upper side is highly polished. Late Eastern Chou.