Post-1918 fixed loop three part construction. Cover, backplate, & loop all test strongly positive for magnetic attraction...so silverplated base metal cover. Crest identified as Calvert Family. Motto ("Fatti MaschiParole Femine") is a three word version of the normal four word family motto based in archaic Italian and dating to AD 1622. Normal American practice for uniform buttons includes mnfg. backstamps. Do we have any idea of the origin of this specialized button type? English/Canadian? Custom made?