Larian Studios Forums Divinity II The Dragon Knight Saga / Flames of Vengeance (English) Divinity II - Flames of Vengeance Malachite Gems as quest rewards?

I heard some quests can reward Malachite Gems, so I have questions.

1: Do the quests that reward the gems ALWAYS reward them, or is it random?

2: Are the gems one of the selectable rewards, or are they "secretly" added to your inventory, like with The Horror of High Hall (in ED)?

3: Which quests can (or do) reward gems?