Glinting Nightseye

It is the best rogue pve gem for combat, next to 8 hit rating gem if you want to get to hit rating cap.

It's worth noting that this is actually quite a viable -tank- gem.

Whilst a lot of tanks favor the "12 stamina in everything" approach for raiding, some prefer a more balanced approach to get their socket bonuses (especially on 5man gear where overall mitigation stats are a bit more handy than pure stamina). 12 stam in blue sockets, Enduring talasites in yellows and that leaves the dilemma of Red sockets.

+Hit is a very valuable stat for tanks which is sadly missing on quite a lot of tank gear (for example, a tank geared from heroics and karazhan only would be lucky to have hit on anything other than her weapon), as it's the only way to increase threat from Sunder (bar +weapon skill). Having it combined with agility is handy too, as whilst it isnt the most efficient stat for a tank, Agility at least offers a reasonable mix between bonus threat and mitigation for one stat.

Whilst some tanks will prefer either +8 Dodge/Parry gems in red sockets, or possible the 4agi/6sta gem, the Glinting Noble Topaz is imo a very viable alternative for tanks that want to fill their red sockets with something to get more +Hit and arent as concerned about maxing stamina at the expense of everything else.

All ratings equal the same percentage for the respective stat for every class at the same level.