This coin has got me stumped it is marked "sigillvm scaltegi" "civium de gelnhausen" "barbarossa gelnhausen" it is marked 986 which is the gold content they used in DUCATs. Also it is engraved "BILL 8-21-71". It weighs 4 Grams and is 3/4". It has been tested good for gold. Any help would be appreciated.