Guerlain Riviera Terracotta Vernis ($22.00 for 0.38 fl. oz.) is described as a “powerful electric indigo blue with subtly metallic finish.” It’s a rich, blue-based purple with threads of lighter violet metallic shimmer. SpaRitual Blue Moon is deeper, bluer, and not metallic. Essie Smooth Sailing is lighter, more periwinkle. SpaRitual Illume has a jelly-like finish, no shimmer.