The mosque is not painted - it is completely covered in ceramic tile. We were very lucky, and got to join in a tour of the workshops with some government bigwigs. The mosque has a team of craftsmen who are constantly restoring the mosque, making new tiles to keep the appearance impeccable.
The main courtyard is in white marble, surrounded by a ring of black. One must remove one's shoes before entering a mosque. After nearly burning my tender, unconditioned feet on the black stone, I really appreciated walking on the cool, white stone!