A pair of photos posted to Chinese microblogging site Sina Weibo and shared by HDBlog.it [Google Translate] show what is alleged to be packaging for an official Apple case marketed for the iPhone 5S but which would also fit the iPhone 5. Text on a paper insert within the packaging indicates that the case is at least partially constructed of aniline-dyed leather, similar to Apple's Smart Covers for the iPad and iPad mini.
This case is made from natural aniline leather. Its appearance will change as you use it. [...]
Compatible with iPhone 5 and 5s.
As the report notes, the informational text included on the paper insert is similar to that seen on other Apple accessories, and the "iPhone 5S Case" name printed on the plastic packaging matches the styling seen on an alleged leaked box for the device itself.
One questionable aspect of the paper insert is the use of a lowercase "s" in "iPhone 5s", as Apple has traditionally used a capital "S" when printing the names of its "S-model" iPhones in plain text. The packaging itself also appears to be rather large considering Apple's usual standard of minimal packaging for its products.
Apple is expected to unveil both the iPhone 5S and a lower-cost iPhone 5C at a media event beginning in just a few hours.