Frankly, I see the reason most items shouldn’t Stack On Top, of themselves is its just not realist to the games world.
Scrolls, AkA Small rolls of parchment cant stack on themselves, why should engraved rocks or gems?
Potions can be stacked(hung really) from a belt. They shouldn’t stack in the inventory, would make zero sense. Why would you need a belt to specially hold potions outside of your inventory(pack back) if a pile of potions took up no more room then 1.
Frankly, I am all for adding a key ring for keys if you have more then 1 key, then I could see at a glance if I have 1 key left.
I have stated before, If you want Gem/Rune stacking, it needs to function how the game already handles stacking small objects. Aka Like Tomes.
Make a few new Objects, Rune Box, Gem Box. They start Empty, First Gem/Rune place Changes the box. Its no Longer Gem Box, its Chipped X Box (1/20), its no longer Rune Box its El Rune Box(1/20). Make the boxes 2x1 in inventory, make them only functional in the Stash. The Inventory icon should update depending on whats inside, SO visially El Boxes have an El rune on the lid, so they are visually different for ease of use and also to reduce likely hood of people swapping them during trades, You would know at a glance if you are getting the Box of Shael Runes because its got its own Icon. Getting swaps for the 1/20 Shael box would still be a bad time tho… Hmm, maybe they Bulging when they are full?
Could also make a Jewelry Box, Similar to the Cube(2x2), but ONLY Holds Jewels, Rings and Amulets(maybe inside of box is a 4x5). Only openable or deposit able while in the stash(so Players cant keep it in the inventory to be always able to throw all the rings the drop in it)
Gem and Jewelry( minus jewels) boxes could even be added to classic. To aid in item storage.
Personally, I would have them sellable by the Act 4 Vendors. Most likely Gems and Runes wont be to significant of an annoyance to store before getting to Act 4, for new players.
Would also make those vendors feel more useful. They look awesome, but currently, they dont really offer a lot for how cool they look imo.