Next up was the base. Looking at pictures, we realized the color of the stone was dependent on lighting. Nathaniel selected Tamiya buff (XF-57) as a good place to start.
Tamiya America, Inc Acrylic Mini XF57, Buff | Horizon Hobby
Acrylic Mini Xf-57 Buff 10Ml Bottle / Tamiya USA
Buff Color Acrylic Paints - XF-57 - Buff Paint, Buff Color, Tamiya Color Paint, C69A69 - Art-Paints.com