10. Gems
Spreadsheet it. I'm serious,
go download a spreadsheet and figure it out. Depending on your gear, you could be gemming any mix of attack power, hit, expertise, or haste. It's easy to spot the times to gem hit: if you're below an important cap. Other than that, only a spreadsheet will tell you what's best for you. If you just want to put a stock gem in every slot,
Bright Cardinal Rubies aren't going to be terrible. The other cool thing about Mutilate is that a PvP rogue wants to also socket all AP, so your gems will match either way.
Use
one Nightmare Tear to meet your meta requirement, preferably in a blue socket that will grant you the item's socket bonus. Choose the item with the biggest socket bonus but that only requires one blue gem. Speaking of the meta gem, you'll be sporting
the Relentless Earthsiege Diamond (RED for short). It sports another 3% increased critical strike damage, and I'm sure you're spotting the trend of "Mutilate really loves crit" by now.