We have recently moved in to a 1920s period property. The crittal windows had all been redone with matt black steel with satin chrome ironmongery. Door handles are matt black. All the switches and sockets are black nickel. We have a few pictures with brass hangers and wire. Recently the radiator valves have started to fail so we will need to replace these and it makes economic sense to do all at once. These are currently basic shiny chrome / white ones which dont seem to match anything. Given the cost I want to make sure that at the least it also improves the decor, however struggling to find the right finish. I keep reading about this rule of 3 metal finishes, given that the windows are black crittal with satin chrome ironmongery, does this count as 2 of the 3? should we consider swopping out the black nickel switches for satin chrome also and then maybe replace the trvs with brass radiator valves to match the picture hangers etc. and keep it at 3? or is black nickel basically same as black elsewhere so matt black/black nickel, satin chrome and brass can be considered the 3 or does it start to look messy..... any thoughts would be appreciated!