Recently I asked around in a German forum about the colours of German destroyers ("Große Torpedoboote") in World War I.
According to the standard text book by Groener, they were painted black until the end of 1916.
BUT: actually they were painted grey already in 1915. This grey was called "Dunkelgrau" (dark grey) and it is the same as on the hulls of the bigger ships. In contrast to the bigger ships also the superstructures of the destroyers were painted "Dunkelgrau".
BUT: this colour was not dark grey at all! It is a light grey, little bit dark the the light grey on the superstructure of German ships between 1896 and 1945. The decks were probably painted black.
In George's review of the HP Models kit of the British M class destroyers (see
here he wrote that British destroyers were also black, but they changed to light grey only in July 1916 (their masts were already painted light grey in 1915).
British destroyers during the Battle of Jutland were therefore black, whereas the German ones were light grey? Until recently I would have thought it was the other way around...