Runes
This page lists PD2 changes for socketables (runes, gems, jewels) relative to the vanilla game.
Runes
All runes are now stackable. Runes can be switched between their stacked and non-stacked forms with cube recipes or shortcuts, and can only be placed in items when in their non-stacked form. Runes begin dropping in their stacked form at the end of Act 2 in Normal difficulty where players should have access to the Horadric Cube.
For rune effects that have been changed, changes are shown in blue with the original effects shown in gray.
The term "high rune" refers to any rune that cannot drop from the Hellforge quest, which is Vex or higher. It is not to be confused with the troublesomely-named "HR" unit of currency, which can be used with any sufficiently-valuable item rather than just high runes.
High runes typically form the core of market trading currencies due to their rarity and general usefulness, while upper "mid runes" (Lem through Gul) are close enough in value to be traded in a similar fashion, especially during the beginning of each ladder season. Below Lem, rune values are too low for individual runes to be practically referred to in terms of HRs, and are traded more often in bulk rather than as individual tokens of currency. Beyond runes, few items are used as ubiquitously as currency, with the most notable exception being Worldstone Shards.
Gems
Flawless and Perfect gems are now stackable. Flawless gems now begin dropping in Act 4 Normal, and Perfect gems can now drop in Hell.
Gem effects have not been changed from vanilla D2, but are included here for convenience.
Jewels
Several jewel affixes have changed.
Also see: Unique Jewels