The corners of the cartes can give an immediate indication of date: square corners were typical of the 1860s and early 1870s, but from about 1875 rounded corners were in vogue. So when taking a digital copy of a carte de visite it’s advisable not to crop off those vital corners. In fact try not to crop any part of an early photograph as clues may occur on the lower section of the print such as the name of the studio, or the photographer's name and location.
The First Photograph, or more specifically, the earliest known surviving photograph made in a camera, was taken by Joseph Nicéphore Niépce in 1826 or 1827. His method was quickly developed by other photographers.
At the time of Niépce's discoveries and those of his contemporaries, Natal was a small obscure trading settlement and it wasn't until the emigration era of the 1850s that the art of photography made an impact on the growing Colony.
The Natal Almanac was published from about 1863 but individual directories giving names of people didn’t commence until 1871. However, there is an advertisement in the 1863 Almanac stating: Brock and Bowman Photographers At Mr J N Wheeler’s New Portrait Gallery, Pietermaritzburg.