I've been unsuccessful in finding a T9 BiS list for Assassination Rogues on any current forum from any private server. So, I have made a tenable BiS list here. I'm sure there will be some disagreement from some people. If you do, please open a constructive dialogue!
Here is an AtlasLoot picture of where to get each item, since the names change slightly between factions, and links for each item.
With the aforementioned BiS list, you should only need 1 Precise Cardinal Ruby and 1 Accurate Ametrine. All other gems (20), with the exception of 1 Nightmare Tear, can be Bright Cardinal Rubies regardless of socket color classification.
Some of you may be thinking that it isn't a good idea to forgo the 4-set since one may arguably have an easier time getting it as well as the perk isn't terrible (5% increased critical strike on Mutilate).
In defense of choosing to ignore it, you gain 171 (102+69) haste rating from the chest and shoulders which converts to approximately 5.2% haste. The 5.2% haste after SnD and 20% melee haste becomes approximately 8.8% haste. This will further stack with Bloodlust/Heroism, Hyperspeed Accelerators, Berserking, et cetera, etc.
I hope this was of some help for some of you. Feel free to contribute other opinions, but be sure to account for any lacking hit/expertise rating as a result of your suggestion, if any.