(ru|Князь императорской крови) was the title introduced in the Russian Empire in 1886 for distant descendants of the emperor. The title was granted to great-grandchildren and their descendants (and their wives) instead of the more honorable "Grand prince/Grand Duke" (ru| великий князь; for children and grandchildren). It was introduced due to a significant increase in the number of members of the House of Romanov, in order to cut the expenses required by the law for Grand Princes/Princesses.
In 1885 Emperor Alexander III formalised the use of titles in the Imperial House by amendment to the succession laws. Grand prince belonged henceforward only to sons and paternal grandsons of the Emperors of Russia, and Grand princess correspondingly only to daughters and paternal granddaughters, as well as to legitimate wives of Grand princes.
One male infant only 9 days old at the time of Alexander's edict thus lost the title. Those Russian dynasts who genealogically were distant from Emperors (as not to be Grand princes) were entitled to titulary Prince of Russia.
Prince John Konstantinovich of Russia (1886–1918) was apparently the only who lost the grand ducal title accorded by convention at birth but removed by Alexander III. Alexander III's own grandchildren, children of his daughter Xenia Alexandrovna, were not yet born at the time of the edict, and accordingly became "only" Princes of Russia from their births, as they were great-grandchildren of Nicholas I (one generation too far) when looking at the male lineage.
All were styled Highness.[1]