Diamond shaped flying object

My boyfriend and I were laying in grass at high school looking at stars ,there were low clouds but not many. All of the sudden I saw a object that was diamond shaped seem to almost float over top of us .it was big almost flew like a kite would ,it was black or dark grey with what looked like circles in each corner. It made no sound and had no lights . As it went over us it continued to fly until it was out of sight, had to have been about 200 feet above us so I got a good look at it,I just don't know what I seen .it was too big to be a kite or drone .my boyfriend had walked across the road ,only about 50 foot and when I seen it I screamed what the hell is that !!! And he didn't hear me at all .,it was like I was muted .hard to explain !