if its center is like a "+" sign straight 90 degree angles --its a finnish good luck * symbol ring -- if it is not its the nazi type symbol. -- the finnish symbols used on their planes was also "blue" not black in color --the finns masterfully played the russians and germans against one another allying back and forth to stay a free and independant country during WW2 -- that and fierce fighting by their small number of troops kept them free from both nazi and soviet control during WW2 .and the russians after the war, ( because land russians took over they kept after WW2)