Again the mystery of finding items in diablo 2. To me it's still a mystery.
http://classic.battle.net/diablo2exp/items/normal/orbs.shtml
Jared's Stone
8 To 18 (13 avg) 18 - - 0 50 3 1 [10]
Normal 24
Level requirement: 18
Quality level: 24
Both these things say something about where it can be found. As far as i know, the monster level in normal, and area level in nightmare and hell, determines which monsters can drop the item, relevant to the item's level requirement. But i'm not sure if that is 100%. Because there is also something called treasure class, not listed on arreat summit, which is a list that tells what every single monster in the game can drop. Which complicates it further.
For example, tal rasha's amulet has an item level of 67, yet can be dropped all the way back in act 2 tomb of tal rasha in normal mode. Which should not be possible, but is. I think it has something to do with the quality level, again which is 26.
So it's a hard one to figure out.
Since a jared's stone has a quality level of 24, look up monsters with that level or slightly above, to rule out other types of drops, and farm them.
http://classic.battle.net/diablo2exp/monsters/
Hell bovines in normal cow level has monster level of 28. That could be a place to try.
http://classic.battle.net/diablo2exp/monsters/act1-cow.shtml