I use Udyr quite a lot in the jungle and usually start build boots+3 then Heart of Gold. After that should I build Philosopher's Stone for more gold, or go straight for my normal build (Wit's End / Randuin's Omen, etc.). I've seen both Philosopher's Stone and non-Philosopher's Stone done.
5 Answers
Udyr's farming is so good that you really don't need a Philosopher's Stone to keep up with others, just the Heart of Gold will do. What I usually do is go boots+3 pots and then Heart of Gold, Wit's End, and then Randuin's Omen. Once there, you can build whatever you really want (for me it's usually Fratmogs).
3I would get it if I were going top lane, but with the jungle Udyr, not really. I prefer going for Mercury's Treads, Heart of Gold, Wit's End... Keep in mind, Wit's End will be your biggest item, damage-wise, until late game.
I don't find the Philosopher's Stone really necessary on any other junglers. If you're getting counterjungled though, the extra gold is nice.
Basically, if you're jungling like a boss, forget about Philosopher's Stone.
If you need the extra boost, then Philosopher's Stone is awesome.
:) Have fun in the jungle!
All depends on how you want to play someone. You can test out builds and see what fits you best. Personally I've seen Udyr grab a Wriggle's Lantern instead of gold per 5 items.
Philosopher's Stone is a NO on Udyr jungle