After seeing many opinions about mining, gemstones and prospecting ...
I would suggest (maybe for the near future) the jewelcrafiting skill, with this could merge less precious stones to make it better. Along with the jewelcrafting skill, rings could be made, and from what I know has space / slot to equip rings.
Following this same idea who has this skill could create stones with skills or status causing it to merge with tailoring and blacksmithing adding the stones into slots in the equipment.
Good game everyone!