In the last few days some images were shared online of what appears to be an unreleased prototype of an iPhone 5s in the same Black and Slate colour as the iPhone 5 from 2012. The image came from Twitter user @DongleBookPro. This particular model was produced in December 2012 just a few months after the iPhone 5 was released and just under a year before the next iPhone, the iPhone 5s was released.

@DongleBookPro mentioned that the use of the same colour as the iPhone 5 model was probably to help bring less attention to the prototype as the only visual difference visible is the True Tone flash sensor as well as the less chrome around the camera surround and flash.

If anything this gives a glimpse into the timeline of iPhone development, Apple were already working on a prototype a couple months after the iPhone 5 was released.