Nokia is preparing its Windows Phone 8 devices for a potential unveiling next month, but a prototype yellow Lumia may have broken cover a little early. WPDang has spotted two images posted at Chinese microblogging site Sina that appear to show a prototype device running Windows Phone 8 or Windows Phone 7.8 with the new smaller tiles Start Screen.

It's hard to say whether this is a genuine device or a clever fake, but some aspects do match previous prototype hardware. We originally saw the Lumia 710 leaked with a proto.nokia.com label attached, something that's visible on this latest handset, and we've also spotted the same markings on a Lumia 800 handset before. The yellow coloring also matches images of a yellow Lumia 800 that were shown at a Microsoft event in France last year and Nokia's admission it was inspired by the CMYK colour group (Cyan-Magenta-Yellow-Black).

We'll have to wait until "as early as" September to see if Nokia has any yellow Lumia devices planned, but for now the repositioned Nokia logo and earpiece coupled with what appears to be a curved screen (like the Lumia 800) makes this either a potential prototype device lacking the new Windows Phone 8 logo or one great photoshop job.