It revealed a contradicting unexpected brilliant colour which hasn't been seen in a long time.
Explanation:
The colour contradicts the sculptural qualities of Michael Angelo master piece with a pressing question among the restorer whether the creator used a secco paint to modify his finished fressco painting after the plaster had dried.
The materials that were used to construct the pyramid by I.M. Pei was steel and glass. I'm sorry if it wasnt much help but that's all I could find on it.