you first need to complete a questline from the jeweler in florin named ardan:
https://imgur.com/a/tGRRqri
the quest that will give the knowledge should be the 5th in chain:
https://bdocodex.com/th/quest/3500/88/

Descobrir como se libera a quest. Você precisa fazer umas sequencias de quest na propria cidade Fiorin, iniciando por Ardan.

https://bdocodex.com/th/quest/3500/88/?sl=1 bu görev serisini npc valentine ile bitirin. Npc Askasha nın devam görevlerini yapın. Bilgiyi askasha'nın görev serisinden elde ediyorsunuz.

Read here

Translation@How exactly does that work with this knowledge, what exactly do you have to do there? do not get there

Not required to get full energy. I skipped this, together with "Caves and Treasures of the Ancient Ruins" knowledge.

None of the other comments helped me, maybe they updated it but this Quest give me the knowledge: https://bdocodex.com/th/quest/3500/111/

直接去找弗洛琳村莊的水晶商人 阿樂丹 會有一個任務 是要恢復甚麼壞掉的寶石
會有三個寶石碎片 要用居住地的煉金工具煉金 把它做出來 再交任務回去
同時會獲得三個武器碎片 接著要去找阿樂丹旁邊的武器商人阿斯卡沙
一樣去煉金工具煉金 做出來 再交回給他
然後接著的任務是他會告訴你他喜歡貿易管理人蘿莉亞 請你給他一顆紅寶石
交給他 最後一個任務 找蘿莉亞交任務 就會獲取知識了~

Bu Bilgiyi almak için Askasha adlı npcye gidip aşağıdaki görevleri sırasıyla yapmalısınız.
-[Kimya] Askasha'nın Silah Tamiratı
-Güzel Mücevher Sever
-Loria Bunu Sever mi?

To get this Knowledge, you must go to the NPC named Askasha and do the following quests in order.
-[Alchemy] Askasha's Weapon Repair
-Beauty Loves Jewelry
-Does Loria Like This?