Stuck on Dark Wizard

ok.. so ive played through this game about 4 or 5 times.. back when my sega cd worked. Recently i started going through it again now that it is emulated.. my question is: how do you get that light jewel from the desert oasis?? i have those elf tears.. ive tried using them at the oasis.. ive tried searching around it.. nothing has worked at all. If anyone here has played through the game recently maybe they could let me know what they did to get it to work... i cant remember what i had to do :-( im thinking theres someone i was suppose to talk too some where... who knows, any help would be appreciated.