Empress of all the Russias, Catherine the Great reigned from l762-l796.
Tsar (man) and Tsarina (woman) of all the Russias
Assuming that you are asking who the Czarina Alexandra's, who was not by right or title an actual Czarina but known as the Empress of all the Russias, grandmother was, it was Queen Victoria of the United Kingdom on her mother's side and Elizabeth of Prussia on her father's side.
Empress Elizabeth of Russia was born on December 29, 1709.
Empress Elizabeth of Russia died on January 5, 1762 at the age of 52.
Her Imperial Highness. Some countries would use Majesty instead, but HIH went over fine with She of All the Russias.
Empress Meishō was born on January 9, 1624.
Empress Kōjun was born on March 6, 1903.
Empress Schuck was born on February 19, 1993.
Empress Eugenie was born on May 5, 1826.
Empress Myeongseong was born on October 19, 1851.
Empress Elizabeth of Russia was born on December 29, 1709 and died on January 5, 1762. Empress Elizabeth of Russia would have been 52 years old at the time of death or 305 years old today.