Cone 6: Cenote is a semi-opaque, sky blue gloss glaze that has a variety of brown crystals that melt during firing. Cone 10: Base color darkens. Crystals become darker and more defined. TIP: SW-166 Norse Blue is the base glaze. For a lighter crystal effect, you may try applying two coats of SW-166 Norse Blue with a third coat of SW-189 Cenote.