That is a very nice example, congrats! To me, this effect is one of the more attractive manifestations of "patina". Seems to be more prevalent in Rolex than other marques.
A friend of mine dropped one of those, from mid ´90s, in to the Baltic Sea. About 30 miles north east from island of Gotland, 100 m deep. Insurance company paid 17k€.... solid gold... Now, go get it boyz
Beautiful scan, I have the same brown stardust with diamonds, very hard to take a scan as this for me anyway.