The middle stripe is a black lacquer insert of approx. 3.5 mm width. The combination of silver and black gives the feeling of wearing that "certain something" on the finger as well.
In order to determine your ring size, you should measure a suitable existing ring with a sliding caliper from the inner edge to the inner edge. If you do not have a matching ring, please allow the size to be measured in a specialist store. Alternatively, you can also order a favorable Multisizer for ring size determination. We strongly advise you against using a ruler or a printed ring measure to determine your ring size.