- Gemstones have MP 1:1 with their gold value. A 100 gp gem equals 100 MP.
- They can be used when it makes sense for the item, and the core and the required slots are filled.
- They are usually used as free capacity, or as decoration that also carries magic.
Open question
Are gemstones pre-charged (they already carry their MP), or empty with capacity = gp value? Pre-charged makes gold a shortcut. Empty makes them good vessels. See Open Questions.
Nord’s gemstones (e.g. in Mountains) also have a grade. For now: use the gp value if the stone has one, otherwise its grade capacity.