A periodic clean with a soft cloth should be all that is needed to keep your jewellery in it’s original condition. No abrasive cleaners should be used as this will remove the protective wax coating that has been applied.
Each piece is coated with Renaissance wax, a product developed and used by the British museum to protect its exhibits and is also widely used by jewellers. This wax forms a hard, protective coating that will either prevent metal oxide forming or, should the piece already have an oxide coating as part of the design, fix the oxide layer to the piece and prevent it from rubbing off.
Lightly brushing the surface with a soft cloth will help to restore the shine to this wax layer without affecting the metal surface patination beneath it.
The pewter used in my jewellery is lead free and cast from new ingots, no recycled pewter is used to guarantee that there is no lead contamination.