Chapter 1 - Non-weapon Proficiencies
Gem Cutting Non-weapon Proficiency
A character with this proficiency can finish the rough gems that are discovered through mining at a rate of 1d10 stones per day. A gem cutter derives no benefit from the assistance of non-proficient characters. A gem cutter must work with a good light source and must have an assortment of chisels, small hammers, and specially hardened blades.
Uncut gems, while still of value, are not nearly as valuable as the finished product. If the cutting is successful (as determined by a proficiency check), the gem cutter increases the value of a given stone to the range appropriate for its type. If a 1 is rolled, the work is exceptionally brilliant and the value of the gem falls into the range for the next most valuable gem (the DM has the relevant tables).