No Charles. Bluing is not Ottoman at all. It is european stlyle.
But as the friend of our friend Ariel says "I have not seen enough of them"
Ariel, in Ottoman empire time, Greeks were living up to Romania and Slavs down to Peloponnese, so I dont mind about clean "ethnic" styles anymore. But a sort walk inside the borders, in local museums and books about traditional craftsmanship, shows an mysterious absence of red corals.
Maybe it is quite ridiculous as idea, but is it possible that red corals were a privilege of Muslims and not allowed to other populations? I know that in Byzantium red color, mainly porphyr, was only for the aristocracy and there was heavy punishment for the commons who used it.
Later, in Ottoman empire, if I am not wrong, emeralds were only for the sultan and his family. I wish someone can tell us more about the social taboos of stones and colors in Ottoman empire.
And please Ariel, let Brussels bureaucrats be. Sometimes, accidentally, they make fair rules, like this. After all these years of hunting them, in the end, the only red corals in Mediterranean we be in kitsch souvenirs and in our precious arms