I was doing some testing with this just this afternoon. In my experience, I tried 3 thumb drives from the same manufacture, same model. Each one had it's own unique device ID.
I was able to set a policy to block 'Disk Drives', and add an exception to allow one specific thumb drive, by device id. I put different thumb drives in the computer, and although it took a moment in some cases, it blocked all of the thumb drives except for the one I had specifically allowed.
The one thing I missed in the instructions was that I had to add the device in the hardware devices section of the policies tab, so it took me a while to get it working. Fortunately, Sandip's last screenshot makes that pretty clear, so you can't miss it!
Oh, the other stumbling block I had was that I tried to grab the device ID of the thumb drive based on the 'USB Mass Storage' item in device manager under USB, rather than the 'Imation Flash Drive' or whatever it was called under the 'Disk Drives' group. Use the Disk Drives item to get the device id, not the USB item.
Good luck!