Hi EJ, you should keep it. The color is really beautiful. You could wear the shoes/bag together with a black or navy cocktail dress, or another all black or all navy outfit. It is a bit matchy, for the shoes and bag to be so close in color, but I think it could work.
If you are getting a second color, I vote for gold. It's not that I don't like the navy, I think it is really lovely. It is just that gold is very different from the one you just bought. But, that being said, there are more gold bags in the world than metallic navy. It is a hard choice. Which would you wear more? Personally, I got purple because I couldn't think of what I would wear the navy with. If you have a lot that you could wear with the navy, then it may be a better choice than the gold, but at least the gold gives you an option to wear with lighter colored outfits this spring/summer. I think that the gold would be very useful.