Spent 4-5 hours over 3 days just killing leeches in Bubu.
Do an hour a day - grab the teleport to the Outpost in the North and bring a scroll of Instant Warp.
My WHM 36 / THF was killing the leeches in about a minute each with 3-4 before rest.
My Divine Skill went up 25 levels in the time which was very useful.
Mind the links and just put a Slow and Paralyze on them. If you get into trouble activate the Warp which doesn't appear to be interuptable.
If you don't focus on getting the Ruby, you will get it eventually. Just don't get wound up about it.
Oh I also got 15 Vial of Fiend Blood for my trouble. ^^