There are 9 different hardware made by the Hermes house. Below is the full table with the different codes for each one of the bags. The most common and versatile are gold plated and palladium hardware which can be combined with any leather and colour.
The hardware is 18-karat gold pleated and it's the Hermes classic.
The palladium is the seecond most used hardware after the gold one.
Permabrass/ Champagne Hardware
Comes in a brass tint that gives the metal a distict colour between gold and silver
Rose Gold Hardware
The rose gold is mostly used with black, grey and natural colour leather
The hardware is made by encrusted diamonds combined with white gold
Black/ Ruthenium Hardware
The black effect is created thanks to a process called PVD coating. It is signature for the Hermes 'So Black' with a dark and shiny hardware.
Brushed Gold Hardware
The gold differs from the normal gold hardware due to its darker and less shiny tones
Brushed Palladium Hardware
With a more matte apperance the brushed palladium is less shiny and mirrory
Or also known as the 'Horseshoe bags' due to the horseshow stamp on the leather near the hardware. These are special orders made on requests for the best clients