This reminds me of the medieval paintings, where they would incorporate a flat halo behind religious figures, such as Jesus and Magadalen. After the Renaissance in Italy, we see less and less of the flat halos (especially in contemporary art, but I could be wrong. It's not like I've seen every piece.). So, I really like how rendered this piece as such - combining old elements with 'new' elements.
The piece itself is over all very stunning. The likeness is uncanny.