Piggy backing on what's already been said, the way I geared up my tanks was to only worry about gems after I got my T9 badge gear. By that I don't mean don't gem, just don't get all concerned about min/maxing. I would actually put in the cheap blue gems to the badge gear bits to fit my current stat needs until I had all 5 of the main pieces I wanted, then started putting purple gems in to min/max.
As has been said you're fine for the beginning heroics, and running those will get you improved gear. The really nice thing about being a tank is that you're queue time for randoms is about 5-10 sec. So you can literally grind badges are fast as you want/can stand. Once you get a few of the T9 bits, then start looking at specifically farming instances for upgrades to fill in the non-tier slots.
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