The base appears to be brass. I use Brasso on brass, it's cheap and can be found in the grocery store or at Walmart in the mops/cleaning aisle. To make sure it's safe on your item, I'd test a tiny spot on the bottom of the lamp first. Don't just wipe it on cause it may take off the finish if it's not brass. Just use it on the base, those animal heads near the bottom look painted, don't get the Brasso on any paint or other parts of the lamp. Cool lamp by the way, I like it!