Gems are already a very highly sought item, especially Pamethysts. No, making them able to spawn UberDia would be a terrible idea. Rerolling charms and crafting already makes them valuable.
Youāre correct, it can be a source for trading. Though, Iād prefre to stay away from stacking. Inventory management should be a thing.
SUGGESTION:
I donāt know how big the āquality of lifeā cube is going to be. Suppose its 20 slots now. Maybe we just make it so 20 Pgems = 1 bag of gems. And cubing that 1 bag of gems does the reverse.
More should be done for player inventory/stashes in D2R. Inventory management was one of the main hindrances of D2.
Inventory management is part of the point of D2ā¦ stackable potions would mean in practicality limitless survivability. Hardcore would be meaningless. Also, excess gold = excess gambling = more valuable items = inflation which is not good for the economy.
I disagree, I think killing the enemies of hell is the point of D2. More time should be spent doing that than managing your inventory. 
Youāre not supposed to be able to pick up every item, nor are you supposed to be able to carry 50 bazillion potions.
Yeah it would be nice if the gem shrines were actually useful haha
They are usefulā¦ take your flawless gems there and get a PGem. PGems actually have decent value - they are used in many horadric cube formulas.
Yet in the D2R beta, more time was spent teleporting to town to empty the players inventory stash than slaying the enemies of hell in public multiplayer groups.
Yeah but they are so common itās hardly even worth it. Especially as so many drop in hell, Iām usually looking more for the lower ones to cube runes so spending time running normal
Sure they can do thatā¦ but thereās a cost to those players doing that. If something valuable drops while they are in town instead of being out with the group, then they miss out.
Iām sure you would like plugy if you pick up that much. Iām not wasting time stashing items that arenāt GG or needed for recipes. Edit: of course thereās some exceptions, like keeping the best MF rings I can find until I have better.
If you are using them in cube formulas you will burn through those āplentifulā PGems in a hurry.
And as a result, players who play with others that do this in public multiplayer games are affected the most in higher difficulty content due to additional player scaling. Another reason that persuades players to play solo/private games.
Sure, but finding the right item level GC to cube is even rarer.
Thereās also a reward for that greater difficulty: a larger share of the loot. I would agree there would be a problem if there was extra difficulty with no reward, but that doesnāt appear to be the case. And as long as thereās one aoe class there, most packs of mobs will go down without too much difficulty.
Gems have always been a part of currency.
Iāll be a supporter of rune/gem stacking solely for easy trades and crafting but I can live without them.
And that is why it might be ok for PGems to be stackable. Like I said in my first post in this thread, everything else (runes, potions, other cuts of gems) should not be stackable.
Personally, I play solo a lot because I simply donāt want to play with other people lol
Just more reasons for players to go back to town. 