What kind of partial refund should I be entitled to? Calling all gold "experts"

This is not about a QVC piece but can I still post about it? You guys always seem to know your info on gold so I thought you could help me out! Much appreciation!

I ordered a beautiful champagne diamond ring set in yellow gold. It was advertised as 14K but when I received it tonight it clearly states 10K gold.

I do have a good relationship with the online seller and I do think this was an honest mistake but I would like to ask for a partial refund since I'm getting a lower grade of gold. Here are the specs:

45 champagne diamonds, total carat weight: 0.5ct
diamond clarity SI1
10K gold, solid, not plated
weight 4.5 grams

Original asking price was $625.00 when it was advertised as 14K. How much of a refund would you ask for? What would be fair?

Thanks!!!!!