Diameter of Royal grandducal serves is 9.5. Marked Kornilov, St Petersburg, Russia in blue on verso. Blue Kornilovs mark 1861 - 1884 for Kornilov Brothers. The factory was founded in 1835 by V.
After 1839 her sons were listed as the owners and in 1886 the company became Kornilov Brothers. They started making insulators in 1862 and this business was sufficiently profitable that more focus was placed om insulators than on dishware. The company was nationalized after the Russian revolution in 1917 and was renamed Porcelain factory "Proletariy" with focus on high voltage insulators. In 1990 it became the "Kornilov porcelain works".