This nephrite and guilloché enamel desk clock - bearing marks for Henrik Wigström and Fabergé in Cyrillic - seems to have been remodelled by another workshop, adding "Cartier style" diamond set hands, Roman Chapters and a central disk of pink guilloché enamel to the clock face..
Image courtesy of Sotheby's London.

Attention to detail is key when looking at Fabergé time pieces...

The majority - namely over 90% in my estimation - of clock movements were bought in by Fabergé from Möser & Cie, a renowned Swiss clockmaker who had set up a retail branch in St. Petersburg during that time. 

In this article I describe and illustrate some of the specifications that make a difference to a piece's authenticity: including clock hands, movements, makers marks and cases. 

Image courtesy Bruun-Rasmussen.