old movie 70s or 80s...

hi! im trying to find an old movie 70s or 80s...it goes like this...a man searching a stone of power,i think red stone or ruby stone,in the end somewhere below the earth.he find a secret organization,i think,and he starts a war,and he goes in a chmber with a throne,he seets,and put his hands in the arms of the chair,eventually he posses great power,kills everyone,but he bunr in the face