Two diamond shaped craft rotating around each other with bright lights noted in broad daylight for 15 min.While flying quad-copters for the day at a school on Saturday afternoon, I turned to the north and noticed 2 lights in the sky that were distinct from the high clouds. At first, I believed these to parachutes or para-motor type craft, but was confused, given the fact that the winds were beginning to make our flights difficult on the ground, and when I called attention to it to my friend who was flying quads with me, she too saw the same two craft and we immediately began to try to match it to known aircraft or explanations.The two craft were seen at an elevation of approximately 40 degrees above the horizon and were due north of my position. The craft were moving in relation to one another with the top left craft from my position being brighter while the second similarly shaped craft was less distinct and even somewhat translucent. After a time the second craft was no longer seen and the brighter and larger craft stayed in view for many minutes. I attempted to film the craft with my on-board quad-copter camera but the lens for both this and my camcorder I had were not at all appropriate to this kind of a sighting and thus nothing was captured. In fact, the quad-copter camera mysteriously did not even have a record of the flight even though I had made certain to activate the camera and there was plenty of space left on the SD card! Early on in the sighting, the two craft were moving quite erratically and in revolutions clockwise around the other as if they were orbiting one another. My first thought was of a parachutist or para-motor craft in trouble with a bad chute then I realized how high these objects were and that it couldn't possibly be one or more chutes. We couldn't identify any noise coming from these craft. The lights were constant in brightness at first and there was no variation until the smaller craft began to fade from view.As we watched, the motion of the bright light transitioned to a smooth rotating motion clockwise and slightly descending to the lower right towards the other object which seemed to rotate with it. The other object maintained it's distance from the larger during this change of altitude. When the brighter object suddenly stopped its rotation, the shape for both was seen as a diamond shape for both craft by both of us. The distinct edges and structure were then apparent and it was obviously a pair of physical objects.The objects were behind the high thin clouds at times (still easily seen through the clouds) and my estimation of their height would be in the thousands of feet in the air. Other conventional aircraft in the air before, during and after the sighting were seen and this was definitely lower than commercial jet traffic but higher than the thin clouds. Given the distance and elevation, these had to be of considerable size. A commercial jet I saw during the sighting at 30,000 feet or so to the west had about the same apparent diameter as the larger bright diamond shape, so the object we were watching would be estimated to have a size approaching 50 to 100 feet as a very unscientific guess. The other object which "dissolved" from view was of a smaller size and perhaps was 75% of the size of the larger brighter diamond shape. I also considered that the sighting might be a jet coming towards me with navigation lights on, but this was ruled out when the slow orbiting motion was observed. No jet or prop aircraft would do this since this would mean a aileron roll to the pilot's left or 45 to 60 degrees (to match what I was seeing) which would then have produced strong movement to the right from my point of view (unless the pilot was doing aerobatics which definitely was not the case here). Additionally, both objects had a long period of hovering in one position coupled with a slow movement to the east by 10 or so degrees over a period of minutes mystified me and made me rule out normal aircraft. I also considered if this was a balloon, blimp, glider or a helicopter. The observation of the two objects satisfied none of these explanations as we both attempted to ascertain what we were seeing. I also considered astronomical causes. No meteor trail was noted. It was not a planet, since the ecliptic was to my back since I was facing due north during daylight hours. It was not a supernova, comet or any other natural sky-borne phenomena that I have ever encountered.Around 14:05 hours Pacific, I pointed a camcorder towards the object and was marking my position in relation to it. The sole remaining diamond shape object was clearly visible with only a few whispy clouds near it and I turned the camera away and then back to the position of the object only to find is was nowhere to be seen. In a matter of seconds, it had vanished.One notable event occurred some minutes afterwards. A lower altitude Cessna or similar style aircraft that appeared to be completely painted black appeared from the north and at a much lower altitude. If overflew us directly at an altitude of around 1500 feet and was flying extremely slowly. I cannot say if this was related, but it certainly caught my interest given the direction of travel and behavior.I have spent a lifetime in around rocket and aircraft systems and have spent 30+ years in amateur astronomy. I have flown in fighter aircraft as a civilian and know the full range of U.S. and foreign civilian and military aircraft from past and current fleets. This matched none of the craft or natural astronomical phenomena I have ever seen or have knowledge of. I cannot say what we saw, but it was certainly an unknown and my hope is that someone else in the area saw it and can add their testimony to the sighting and perhaps identify what it was.