Engraved or etched silver is sometimes oxydised to bring out the engraving of pattern. To clean it is not that difficult but needs a little bit of care. Do not use a silver cleaning solution as this will remove or discolour the oxydised area!
This cuff is part of my Manu Scriptum series and is a prime example. In order to see the written text I have oxydised and given its matt finish but the rest of the cuff oxydises as well over time! As it has a matt finish I use a common pot or dish scrubber (see below left) to clean the top surface without touching the etched part as it is a bit lower. Use a gentle motion in the one direction, no need to apply much force at all to get it back to its original condition. Take special care on antique pieces with very fine engravings as it can blur it if you apply a bit too much force or do it too often.
If the piece you want to clean has a polished surface then use any Silver Polish Cloth (above right). Gently rub the surface until all it is back to a uniform shiny and clean surface.