Yep, it seems that it is needed for access to at least one door to complete the Kirgaxx(sp?) quest. One which I respectfully shelved until after the Underdark. Nasty Liches!

Have found a number of rogue stones, multi-colored gems, and when i do an identify on them it says its rare for some gemjump use or something like that. Is there any reason to collect them? Another gem that seemed rare in the description and high in price is something like kings tear drops? Any use with that?

Thanks for all the help

Try going into one of the houses on the Bridge District with one. It is on the lower third of the map. Enjoy . . . might want to save . . .

Not if you have a kensai/thief in your party . If you do, you can kill them all without getting more exp and items by going to underdark.

I think that there may be two different instances where a rogue stone. So you should probably hold onto one or two. You will also need a diamond and a belijuril stone sometime in the game (perhaps). You should be able to sell everything else.