Microsoft is interested in bringing trophy-like Platinum Achievements to the Xbox ecosystem, based on the latest information.
Speaking during the latest episode of The Xbox Two, co-host Jez Corden mentioned that he has talked with an Xbox executive at Gamescom specifically regarding the introductio...
The diamond achievement means it’s a rare achievement (something like less than 5 or 10% of people have earned it). The platinum trophy signifies you have earned every other available trophy for the game (excluding DLC trophies). Xbox used to have something similar on the 360 where you could see the games that you earned every achievement on.
Steam kind of does, I mean, if you have the achievement showcase on your profile, it'll totally say how many games you've gotten all the achievements for. That's about it though. Steam doesn't seem to care all that much about achievements.