The mosaic were created in second half of 19th century according to the original work of T.A. Neff (1805-1875). It was done by V.A. Beringer, A.P. Rogov, and F.A. Yutsevich.
(Website: http://eng.cathedral.ru/isaac/ubranstvo/mosaic )

T.A. Neff (Carl Timoleon von Neff) (1805-1875)
Neff Timofey Andreevich, who was a known and popular artist among St. Petersburg high society, painted "Birth of the Virgin", "Advent of Holy Spirit on the Apostles", "Resurrection of the Lord", "Entrance of Our Lady into the Temple", "Exaltation of Life-giving Cross of the Lord", "Jesus Sends His Image to Augarius", and "Intercession of the Holy Virgin". They stand out with their excellent technique, spiritual beauty of the images, refined color and lighting effects....
For more information see: http://commons.wikimedia.org/wiki/Category:Carl_Timoleon_von_Neff