Dingy gold after soldering?

I am an experienced silversmith, and normally work in fine or
sterling, argentium, copper, or brass.

I recently worked on a special order for a customer in 14K gold. I
don’t have a lot of experience with gold outside of the classes I
took, because of the expense.

The process was soldering a thick tube bezel (not the cup type) to a
gold coin, for setting a small sapphire. It went well, and I finished
the piece without incident. Except after pickling…no matter how
much I polished - with rouge, then cleaned, then buffed…it still
looks really dingy compared to before the soldering process.

I bought the stock from Rio - so I feel confident it’s really 14K.
What did I do wrong? Help!!

Bonnie Alvarez
Owner | Designer
Birth Designs