As CR pointed out, it is part of the set. The dial is made of solid gold and engraved with floral patterns which I believe the name of the edition is Lange 1 "floral". I knew its existence but never stumbled upon one of the owner. Again, many thanks for posting this fantastic piece. It is a treasure
I do not think there are many watches that can top the ZW Lumen. In metal it is absolutely gorgeous, such badass watch. The smokey dial is breathtaking and suits very well to Zeitwerk. Closely followed by the white gold variant.