A reportedly leaked SIM card tray has offered the slightest suggestion that a 'gunmetal' grey option may be in the works.
Following the leaks of a champagne gold casing, these new pictures leaked out of Japan, may just indicate that a fourth colour is on the way, but naturally this should be taken with a large mountain of salt.
The iPhone has only ever been available in black and, more recently, white so the roll-out of new colour options for the iPhone 5S would be noteworthy.
In fact, it may turn out to be a headline feature in what is expected to be more of an incremental update from Apple.

Gung-ho

The new gunmetal photos arise from ASCII JP, the same source as the initial champagne gold casing leaks, so they shouldn't be dismissed out of hand.
The iPhone 5S is likely to be launched at a yet-to-be-confirmed Apple event on September 10, where we could also get our first look at the cheaper, more colourful iPhone 5C.
Do you think Apple go gung-ho with a gunmetal iPhone 5S? Let us know your thoughts in the comments section below.