Bone is a matte cream color (Bone is a good name for it, actually).
Sandstone is a matte nude color.
From left; Bone, Sandstone
I reviewed Amethyst, Golden Orchid, and Romance here. The formula for these seem a little different. They are less buttery, but still very smooth.
These make great transition/blending colors (to transition from a bright or dark color on the moving lid into the crease and under the brow), and Bone makes a good matte, highlight used under the brow. They also work well as simple nude colors to brighten the lid.