Like it says on the tin. Dependent on Miner or Blacksmith or Tailor or some combination of the three. Final benefit would be a chance to paradoxically increase gem size when cutting.
Proposed progression:
1. Dexterity +15 and Psyche +15
2. Increased chance of success when cutting gems
3. Increased chance to mine out gems
4. Further increased chance of success when cutting gems
5. Chance to increase gem size when cutting
There could instead be bonuses to gilding with gems instead of some of these options.