Vintage fine cloisonne cranes and koi fish

I am looking for anyone who knows anything about this piece, The stamp under the tail says "lver 925" the only thing one would put over sterling silver is gold, right? The piece measures 13"Long x 11 "Height x 7" Wide. There are no other marks on the piece, it was my grandfathers and was found in an old truck it was heavy black in color when found. No one in the family has ever seen it before. I if anyone knows anything or has ever seen one like it I would appreciate any info.