Diamond Plate™
Diamond Plate is an especially hard sort of lacquer coating developed by Williams that protects the playfield even better than mylar since the transparent film often started getting scratches or bubbles after years - not so with DP. Diamond Plate was introduced as a trademark by Williams in the late 80s when they experimented with it on a few games of a series, producing a limited number of playfields with Diamond Plate on it while the majority of games still came with mylar. Of course, these rare DP playfield are sought after! Terminator 2 was the first game to feature Diamond Plate on the full production run. The Diamond Plate coat on late 90s playfields is said to be of lower quality than that from the late 80s till the mid 90s.