Plates were manufactured by https://asiamedals.info/threads/history-labels-i-marks-of-hattori-watch-shop-tokyo.19361 in three different sizes (1st, 2nd and 3rd class of award).
1st class award plate has diameter approx. 22.5 mm.
2nd class award plate has diameter approx. 20.5 mm.
Diameter 22.5...