Steel inlaid jewellery can be prone to oxidisation especially if the piece has been subjected to moisture, red rust will show on the surface this will need to be removed with light steel wool. The surface may then look grey, this can be coloured black using a commercial available gun blueing solution. After washing and drying using a wax polish such as Renaissance wax will protect the surface for the future. The silver inlay may also oxidise and can re revitalised by wiping over with a silver cloth.
Silver with inlaid gold pieces will over time look dull and could if left out in an oxidising atmosphere have a grey surface. Firstly clean by dipping in a commercial silver cleaning solution follow this by brushing with an old tooth brush with a cream cleaner or stainless cleaner such as Astonish oven & cookware cleaner. Rinse well before wearing.
If your piece has had gold leaf applied to the inner part of a pod it is important to try and keep the gilded area dry and prevent getting abrasive substances or solutions onto it. Clean using solutions or pastes on a cloth then wiping with a damp cloth to remove.