DON'T POLISH IT!!
Kirk Smith didn't like highly polished silver, he wanted his work to look old, I think it would greatly and negatively affect the value!
Most of his concho belts sell for 2 to 3 times than what you paid and a few for much much more.
He unfortunately lost his life in 2012, his work is highly sought after, here's a blog that tells his story and how he came to make silver items, his son Raymondo Joe is also a silversmith and carries on in his father's footsteps.
Native American jewelry artisan Kirk Smith created a long-lasting legacy in a tragically short life. His pieces are highly coveted and collectible, and his story is an interesting one.
doubledranch.com