What drop does item boost rarity stat affect?

[Player 3]

During hunt it seems that we get either crafting mats that drop from monster we kill.
It doesn't looks like there is any quality or rarity to them, just 2 types (ore and hide). Then at the end of the quest we open a chest which rarity seems to depend on the chest rarity boost stat.

So i was wondering other than the rarity of item produced in town, what drop does the item boost rarity from the residents affect ?

[Azaphena]

Hmm, maybe it affects if you get a gem and advanced material or not, they are a bit rare, but dont know...

[SilentDeath777]

It affects the actual rarity color from rare up to ancient types of weapons or armors.

[Player 3]

From chests? I seem to get much better result with the chest rarity boost stat to get more higher rarity chest in that case while removing most of my 2k + item rarity boost didn't seem to affect the result much (if at all). It seems mostly dependent on the color of the chest you pick.