Fine silver is 99.9% pure silver and is very resistant to tarnish.  Sterling silver is 92.5% silver and 92.5% copper.  Argentium sterling silver has some of it's copper content replaced with Germanium making it considerably more tarnish resistant than traditional sterling silver.

Enamel.  Due to the unpredictable nature of enamel there is slight variation in the depth of the two black and white swirl accents