Hi guys,
Several years agao, I saw a Russian imperial garde helemt for sale, it has the distinctive german kurassier pattern and look, but instead of a single eagle as in the Imperial German Garde du Corps or Garde Kurassier, it has a double headed eagle, symbol of the Tsarist Romanov dynasty.
Cant find the original item now, seems that its pretty rare, but managed to dig these pics of a REPRO Imperial Russian Garde a Cheval helmet, perhaps this helmet is an Enlisted Man's, it has the exact look of the Prussian EM kurassier metalhelme.
It seems that pickelhaube was picked up/copied by other countries as well, I read that the Chilean soldiers still wore their german pattern haube all the way to the 1950s, even their uniform bore a strong resemblance to the Prussian dunkelblau.
Cheers,
Mush