Cone 6: Sandstone is a matte, off-white glaze that contains a variety of brown crystals that melt during the firing. Thicker application and heavy crystal concentration will produce more glossy blue/purple variation. Cone 10: Color darkens. Glossy blue/purples become more prominent. TIP: SW-172 Macadamia is the base glaze. For a lighter crystal effect, you may try applying two coats of SW-172 Macadamia with a third coat of SW-176 Sandstone.