Hi Toby,
I'm sorry that you weren't happy with the chain. I don't know why it would discolor because it is solid sterling silver, of course it was also oxidized to match the finish of your pendant, so perhaps something happened to the oxidation. I've not had anyone else send me a message about that, but I'm curious to know what might have happened.
I know you said you threw it away, but might it still be in your garbage somewhere? I'd like to see it so I can investigate what happened to it. If you still have it, please let me know - you can still send it back for a full refund.
Thank you so much and I'm sorry for the disappointment. -Norma