I contacted Brembo a while ago and this was their response:
The coating used at the BMW M caliper has an oxidation as a base layer and on top a liquid paint. This paint can change its color if it is being confronted with higher temperatures. The paint code is GOLD 1PR (no correspondence to Pantone references etc..).
Unfortunately the paint code
GOLD 1PR does not provide us more information if it only used internally by Brembo.
On their website are also 5 reason why not the use repainted calipers:
https://www.brembo.com/en/company/ne...alipers-brembo