These initials are hand pressed and oxidized. The pressing method causes the "letter" to be raised over the disk's surface and the oxidization process creates a wide variety of tones.
The colors produced by the oxidization process have wide range and can come be purple-magenta, orange, gold, soft blue,cobalt blue, grey, brown, black.
The process is natural and creates a one of a kind look for each piece.
How long will the patina keep? The piece is sealed with a tarnish resistant sealer. However, due to the nature of sterling silver, overtime the sealer will wear off and the sterling will do what sterling silver does.