2d6	Result	Defined Trade Good	Unit Increment	Base Price GP
2	Rock Salt/Compressed Coal	1d6 x 7	5
3–5	Riverstone	1d6 x 6	10
6–8	Graphite/Quartz	1d6 x 5	20
9–11	Jade	1d6 x 3	30
12	Alabaster	1d6 x 2	45

These are lots of non-precious stones. Players wishing to dabble in precious stones can purchase them on an individual basis using the normal rules for pricing.