From the Heian period, these are heart-shaped "inome" (boar's eye) and six-leaf nail covers, also used on sword guards. I am offering two for sale! One has a very valuable inscription on the back! In Zen, an Enso (circle), symbolizing emptiness, is drawn, but unfortunately, the center of the characters has faded and is unreadable. The material appears to be shakudo (copper and gold alloy) with gold plating. Dimensions: 10.8 cm x 10.8 cm x 1 cm Nail: Approximately 9 cm long