Hello, mates! It seems that is german, indeed. Look at the cross and you'll find the differences. But is very similar to the WW2 Romanian belt buckle, one of the most rare, in fact. I'd die for one of those... As far as I know, those were initially worn by the Royal Guards Regiments (Pioneer & Infantry guard branches) with the title B.G.R. (Batalionul de Garda Regala) or so, with a true 'pride' among the soldiers on the front. But most of the soldiers wore a plain buckle, i've heard. Congrats to the OP whom I envy honestly.. They can found by accident those treasures in Russia and Ukraine, imagine that... Here's some pictures of the romanian ones that I treasure most:
http://gmic.co.uk/uploads/monthly_02_2013/post-11688-0-66018200-1361634422.jpghttp://gmic.co.uk/uploads/monthly_02_2013/post-11688-0-66954900-1361634432.jpg