PoE2's economy uses crafting orbs as both crafting tools and trade currency. Prices are league-volatile and reset roughly every 3-5 months, so always check the official trade site for live values rather than relying on fixed ratios.
The most important behavioural change vs PoE1: the Chaos Orb removes one random modifier and adds one new random modifier - it is NOT a full reroll. This has been the behaviour since launch.
Transmutation: Normal -> Magic (1 mod). Augmentation: adds a 2nd mod to a 1-mod Magic item. Alchemy: Normal -> Rare (4 mods). Regal: Magic -> Rare (+1 mod).
Exalted: adds a new random mod to a Rare without touching existing mods. Divine: rerolls the numeric values of existing mods (not which mods). Chaos: removes one random mod and adds one new random mod.
Vaal: permanently corrupts (random outcome). Annulment: removes one random mod. Orb of Chance: Normal -> Unique, or destroys the item. Fracturing Orb: permanently locks one mod on a Rare with 4+ mods. Mirror of Kalandra: perfect duplicate of a non-Unique item (rarest).
Since 0.3.0 many orbs come in regular -> Greater -> Perfect tiers, each forcing a higher minimum modifier level. Essences were re-tiered to four (Lesser/Normal/Greater/Perfect) and add a specific mod by tier.
Newer crafting items include Hinekora's Lock (foresee the next currency outcome), Soul Cores (socketable augments), Bones / Desecration crafting from Abyss (0.3.0), and Verisium plus 13 Alloy currencies from 0.5.0. 0.5.5 added 17 Soul Cores (13 Jiquani, 4 Atziri); Atmohua's, Cholotl's and Zantipi's Soul Cores now convert 40% of requirements (previously 20%).
Verisium also powers Runeforging, which adds Runic Ward to armour at the Runeforging bench.
Orb of Alteration is not in the active game - PoE2 has no currency that rerolls a Magic item's modifiers.
Orb of Scouring was removed - there is no scour-to-white currency.
Many other PoE1 orbs (Blessed, Engineer's, Harbinger's, Binding, Horizon, and so on) are not part of the PoE2 system.