No, they still exist. Someone in guild linked their intel goggles with a mastery hydraulic and hit cogwheel or something like that. tbh they arent al they're cracked up to be, since you cant reforge.
That was probably the Cogwheel gem you saw. There is one that has mastery on it. My guess is that Hydraulic gems are going to be implimented at a later date, as an upgrade to the cogwheel. After all they only have blue gems out right now with epic to be added later. Why wouldn't it be the same with cogwheel?