NYX Mermaid is a neutral aqua with a frost finish that is permanent and retails for $6.00. In comparison, Natasha Denona Golden Aquamarine (86P) is a warm aqua with a frost finish that is permanent in palette and retails for $29.00.
Natasha Denona Golden Aquamarine (86P) is 85% similar — it is more shimmery, darker, more muted.