How to color grade gold
Two thoughts: 


Go to images.google.com and search for "gold".  Find something you think is gold-colored, check its RGB values, and then use that as a target for your gold.  Many editing programs have the ability to aim one color toward another, so you can select a range of colors that your camera thinks of as gold and then aim it toward what you think of as gold.  
Perhaps the reason why Apple's high-end iPhones are rose-gold instead of regular gold - they want pictures to look warm and rich no matter whose camera is snapping the image


Ultimately (and perhaps this is your best answer) the eye very much judges color on a relative basis.  See http://www.archimedes-lab.org/color_optical_illusions.html. To get something that really looks gold, you have to have both the right target color and the right complementary contrasting colors around it to make it really look gold.