interestingly, both Apple and Dell used Trinitron CRTs in their monitors for a while... I'm at work right now and I have an old 17" Studio CRT on my G5, and these use the Sony Trinitron. I guess the 17"s are tecnically DiamondTron, so I'm not sure if there's a difference.
Either way, my Dell at home is a Trinitron, and the Apple CRTs that match the old G4 towers are Sony tubes as well.
Its surprising how many manufacturers use Trinitrons in their monitors, but easy to tell. There are two lines running horizontally across the display - about 1/4 of the way from the top and 1/4 from the bottom.
Once I saw these, I saw them every time I sat down at one, so I started noticing them on what seemed like every PC in our computer labs...