Brass substrate is electroplated with 18k gold and then dipped into acid to create the subtly destroyed surface. The concentration of the plating solution, air temperature and time in the acid bath all play integral roles in the final result and exist in a delicate balance. No two items are the same and these nuances / variations should be seen as a characteristic of the product.
Black Sterling is achieved by the oxidation of sterling silver. This blackened state will fade depending on skin type and sometimes quite quickly, the faded look can be considered an enhancement but we will be happy to help teach you how to re-oxidize your pieces if you prefer the pure black finish. Additionally, please note that Black Sterling tends to look darker in photograph then in person.