I first saw them about a year ago over the willamette river. the first of three that i saw, was hovering over the river at about 300 feet and proceeded to travel north slowly moving in a straight line with kind of a jerky motion from side to side as if it was changing direction in very small jumps but still going in the same direction. it traveled north for maybe one mile and then shot straight up to a high altitude and seemed to join with another craft was hovering to the north west. after about ten minutes, it separated from the other craft and descended to around 200 feet and illuminated the whole city block with a white light and moved over an office park and shot over the river to the east, and then joined up with a third craft, then flew together to the east. they were diamond shaped with a strange glow that would pulsate and seem to change color but i was unable to pin down a specific color. it was really odd. also, the object also seemed to be in more than one place at a time. as i was watching it, it appeared to be jumping to random places around it, not far, just a little bit, but enough to definitely notice. when the two objects came together, the light of the one that was at a higher altitude, glowed a lot brighter when they came together.