The figure is wearing a medal of the Order of St. Anne, 2nd Class, with a ribbon. This medal was established in 1816 and was awarded to diplomats and civilians of a certain standing in society.
Even more interesting is the Turkish order of Iftihar Nishani also worn by the figure. The order was established in 1831 by Mahmud II. There were two versions of this medal, and all were attached to the red and green ribbon typical for Turkish military dress.
The relations between Turkey and Russia were poor until 1830, when Nikolai I reached some agreements between the two countries.
The multitude of brilliants on the medal signify his importance, and the paper in his hand may be a contract.