DISCOLOURATION OF 9ct GOLD Jewellery

I bought a ring from American swiss in 2004, a nice 9ct diamond cluster ring. the ring changed color and is now bronze, not gold anymore. I took it to the store in Menlyn mall explained, how long ago I bought it and I don't have the slip, but if you check on the account, you will find proof of purchase, store manager says bought too long ago, I need to retain proof, cannot assist. I also purchased a pair of earrings from the store in 2012 also 9 ct, but this I purchased on my credit card so I did not keep the proof, again, they cannot assist. <br> So it is clear they are selling cheaply made goods that they claim are gold and discolors after a few years, even when kept properly. I would recommend to boycott all American swiss stores as they cannot assist with their damaged faulty goods years later.