Blue Onyx is a blackened blue with an indigo blue shimmer and sheen. It’s more of a satiny finish than metallic as described. This shade was very, very sheer when applied dry, and it doesn’t look all that blue either. When I dampened the product, it came out more vibrant and the blue came to the forefront. It reminded me of MAC Blue Storm. Givenchy Lune Mordoree is also similar but a touch purpler.