Hi there! I have sterling rings (plain bands) that my manufacturer annealed for me so they are soft for stamping. A few of my customers have complained that the rings are turning their fingers green 
Do you think this is due to copper oxides brought to the surface when annealing? Maybe they “over” annealed? If so, would pickling them help? Also, would annealing at a lower temperature for longer be a better option?
Thanks for your help!!!