To upgrade a rare or unique item in Diablo 2: Resurrected, you have to make a particular Horadric Cube recipe. The recipe varies depending on the item you want to upgrade, but it always involves a Perfect gem, and those don’t drop on Normal difficulty except at the Hellforge, where you always get one. It’s possible for them to drop randomly from Act I on Nightmare onwards, but highly improbable that early on, so you probably won’t get your first random Perfect gem until you’re quite some way into the game on Nightmare difficulty.
Upgrading a rare or unique item leaves its modifiers untouched, but improves the base weapon from Normal to Exceptional, or from Exceptional to Elite. So, its basic stats, such as damage and defense, will improve. If those basic stats are subject to percentage based modifiers, then the upgrade can make a very big difference indeed.
The recipes for upgrading rare and unique items are as follows:
Rare Items (yellow)
Normal rare armor to Exceptional
- Normal rare armorThul runeRal runePerfect Amethyst
Normal rare weapon to Exceptional
- Normal rare weaponAmn runeOrt runePerfect Sapphire
Exceptional rare armor to Elite
- Exceptional rare armorPul runeKo runePerfect Amethyst
Exceptional rare weapon to Elite
- Exceptional rare weaponUm runeFal runePerfect Sapphire
Unique Items (gold, which looks more like pale brown)
Normal unique armor to Exceptional
- Normal unique armorShael runeTal runePerfect Diamond
Normal unique weapon to Exceptional
- Normal unique weaponSol runeRal runePerfect Emerald
Exceptional unique armor to Elite
- Exceptional unique armorLem runeKo runePerfect Diamond
Exceptional unique weapon to Elite
- Exceptional unique weaponLum runePul runePerfect Emerald
