All jewelry is crafted from either fine silver, sterling silver, copper, or brass.
All earring posts/hooks are sterling silver.
Many pieces have an intentional patina, and over time or with heavy use this can darken or wear away revealing the metal. Lotions, moisture, oils, soap should be avoided if possible to retain the patina.
For jewelry that does not have a patina: Store jewelry in a box or low-humidity area to slow oxidation/tarnish. A jewelry polishing cloth can bring back shine if desired.
Blue patina jewelry is handmade in copper, painted with patina and sealed with clear matte lacquer. The nature of the patina, even though sealed, is ephemeral in nature and can darken over time.