MAC Objet d'Art is a warm copper with a metallic finish that is permanent and retails for $20.00. In comparison, Natasha Denona Luster (375M) is a warm copper with a metallic finish that is permanent in palette and retails for $29.00.
Natasha Denona Luster (375M) is 90% similar — it is less shimmery, lighter, warmer.