These cases could easily be detected by atypically styled upper kanji 勲 - Merit.
Comparison with a "typical" inscription for "early" (1888-late 1930s) cases (on the example of 6th class cases).
Comparison with "typical" inscription for "late" (late 1930s- 2003) cases.
Currently known...
3rdclasssacredtreasureawardedin1956
case for sacredtreasure order
inscription styles of sacredtreasure order
japanese awards and decorations
japanese medal
japanese order
japanese order of sacredtreasuresacredtreasure order
勲三等瑞宝章
勲六等瑞宝章
瑞宝章