Second, rings, necklaces, amulets and jewels cannot be upgraded.
That is to say, point to the item with the mouse, and if there is a name behind the item base, the yellow or dark gold item marked with the words "ordinary" or "extended" can be upgraded. The "elite" is already the highest level and can't be promoted any more.
Third, red life potion, blue magic potion and purple recovery potion can also be "synthesized" with 3 bottles of the same level and 1 bottle of more advanced potion.
Low-level runes can also be synthesized into high-level runes through formulas.
The two are somewhat similar to "upgrading".