Stealth Question

I want to try a Stealth-centered Rogue, but I have some questions. Does Stealth only apply to Concealment, or is it scattered among different skills and bonuses?

The unique ring: Pitfighter’s Gull can do Stealth, too.
Casting Smoke Grenade increases Critical damage by x45% for 6 seconds and leaves a cloud of shadow. While within the cloud, you get Stealth once per second.