In a library of President Yeltsyn the originals of the diaries could be found. But they only cover the time until 1906. The printed editions of his diary cover his records until his last days in 1918. So, where are the originals of the diaries for the 1907-1918 period?
According to Russian Wikipedia, the originals of the diaries (50 notebooks, from 1882 to 1918) are stored in the State archive of the Russian Federation (fund 601), as a part of the so-called Novoromanovsky archive (i.e. the New Romanov archive). There is no mention about the Yeltsin library.