A very nice piece.
Patina, tarnish.
Obverse: Polish-Lithuanian-Welsh coat of arms shield placed on a grave with a cross and crown of thorns, in the rim a legend:
TO THE RUSSIAN BROTHERS MURDERED BY THE MOSCOW TSAR FOR THEIR LOYALTY TO THE CHURCH AND POLAND;
Reverse: Open book with inscription MARTYROLOGY POLAND / LORD and names of several people, around PODLASKIE AND LUBELSKIE VOIVODSHIP / POLUBICZE - DRELÓW - PRATULIN
Bronze, diameter 64 mm, weight 100.2 g.