I haven't really tried, but I have an abundance of stones. I was previously stopping my bot from going past 30+ because I only used the rift profile to level gems from 1-30 then I took over manually. My DH is solo 41, Monk solo 32(he can do 35 atleast), Crusader solo 32(probably capped, not the best geared could do better with upgrades despite having furnace but a crappy phalanx shield/strongarms) a grift 34 apoc wiz(don't see how the bot would ever be able to figure out how to make this work without some extremely precise routines. WD solo 35(Probably go a bit higher, haven't played since first month of patch).
I am going to let my DH run and see how high he goes, I'll have to hide my pre 30 stones on another char so he can still start from the bottomand work his way up. though I still see it vastly coming down to the same as any manual player does, Map roll, Mob density, Unique affix rolls. I have been manually grifting more then I ever have lately and one thing I noticed(i wear countess amulet 10/100/700dex socket botp gem) so jailers are no issue but I Remember them being shitheads. The fact that thunderstorm mobs can 1 shot you from off screen when you cannot even see them, Part of me loves current DH setup but its flimsy. Drop sentry and hide....But with the new changes in 2.1.2 we can no longer hide, How do we deal with a 1 hit KO thunderstorm that you need to basically vault around nonstop til the elite/unique dies? I don't think it is fair that a monster can drop a thunderstorm on the player before the PLAYER can even SEE the uni/rare(im not talking about the packs you can multishot a room to see whats in it real quick, I mean the ones that are literally down a straight hall, no barriers no hiding that even with precaution you can still be 1 shotted. Because of this a DH is required to run Awareness just in case, if you get hit with tstorm you must resort to dropping sentries and hiding, waiting to kill it or awareness to reset.
Anyway, I guess once I see how my DH goes, I will take all my chars and see if I can rank some gems up, be it 60% or 30% chance who knows. My DH gems are only rank 40-43 because I chose to upgrade my zdps wd gems first which was prob not the best idea. /end rant sorry.