Green scotch brite pad works pretty well, assuming you are after a brushed finish. Go light, and brush in one direction until you start to see the scratches fade away. I've never used a sanding pad but i've heard they work pretty well, around 320 grit. This is controversial, but if you want to prevent scratches on your clasp, especially for Speedmaster type clasps that are mostly flat, 3m paint protector film works awesome, IMHO. You can buy sample sizes off Ebay for pretty cheapPurchases made through these links may earn this site a commission from the eBay Partner Network
I bought a tool off eBay years ago for this purpose. Not sure what it's called, but it has Fiberglass like bristles. You just make strokes on the brushed finishes with the grain until you get the desired results. Works well.