Diamond-shaped UFOs are infrequently seen UFOs that often display colorful lights; capable of moving quickly or slowly and able to perform impressive aerial maneuvers, these ships are most active early in the morning. Green, blue, orange, and red sparkling, flashing, or unblinking lights have been attributed to diamond UFOs. Unlike diagonal crafts, which break off of triangular UFOs, these types are very large and often seem to emanate light from within. Like cigar and box crafts, diamonds are associated with time jumping, though encounters result in lost time. When these ships appear in rural or wilderness settings, they can sometimes be seen releasing a thick, laser-like light from the bottom of the ship that reaches the ground; this light is believed to be related to abductions and/or research/material gathering. Beams reportedly come from windows that open and close like an eye. 

Some believe that these crafts transport important individuals or harbor computers that gather detailed information on the Earth, its environment, activity, and inhabitants; others view them as biological research ships that abduct lifeforms for study or other unknown purposes.