Close examination of the present lot reveals that one pendant has a slanted section at one edge. This is a special characteristic of Western Zhou circular jades, discussed in Special EXhibition of Circular Jade, National Palace Museum, Taipei, 1995, pp 21-22, where the author notes this chisel-like beveled edge on Western Zhou circular jades is a distinctive feature of the period that has long been ignored or taken as a characteristic of imperfection in the workmanship.
The most intriguing feature on the present lot is the design of four pairs of confronting birds impressed, possibly in black ink, around one side of the pendants. As painted or impressed designs on jades are not known from the period, this technique was possibly used to sketch a design that was intended to be carved.
It is not entirely impossible that this impression is original to the jade pendants, as ink can actually be preserved for a long period of time. See two jade huan, excavated from the tomb of a Zhongshan king during the Warring States period, in Pingshan county, Hebei province, each well preserved with two characters written in black ink on one side, exhibited in The Cultural Relics and Art of the Ancient Zhongshan Kingdom, Shanxi Museum, Taiyuan, p. 105. The present impressed design of confronting birds also closely resembles the casting design on Western Zhou dynasty bronze bells, such as one published in Zhongguo wenwu jinghua daquan qingtongjuan [Compendium of Chinese art. Bronzes], Taipei, 1993, no. 581.
While jade plaques carved with a similar design are known to exist, such as one attributed to the middle Western Zhou dynasty to early Spring and Autumn period, excavated from Liangdai village, Hancheng, Shaanxi province, exhibited in The Cultural Grandeur of the Western Zhou Dynasty, National Palace Museum, Taipei, 2012, cat. no. 137, no examples, of the exact design appear to be recorded, which also raises the possibility that the design could have been impressed at a later date.