As you may know, Nokia recently launched Nokia Lumia 625 which has the biggest screen size (4.7-inch) in the Lumia range of smartphone. Now, someone posted a picture on Weibo showing a very big screen with Nokia branding on it.
According to the source, the screen is 6-inch. What is interesting is the small bezel surrounding the screen and notice that it might have a front facing camera. Hopefully, if this becomes a reality, it will come in Full HD.
From the picture, it looks like it was taken in a clean room environment. So, I presume that it might be just an R&D lab or (better) a production line.