Refund for a ring at Sterns

I have bought a ring at Sterns Mall of Africa in February 2021 for my wife. She started wearing it on the 4th of April 2021, within 7 days the ring started changing colour. I took the ring back & i was told it will be booked for repair, I told them I need my refund but they told me I won’t get anything refund. I was told the ring will only get cleaned after 6 months but it shows problems within 7 days. The store is forcing me to take the ring & I was told I won’t get my refund, the policy stated that any item can be returned within 6 months if there’s any fault. All I need is my refund, I can’t take this ring back as I am afraid of similar problems to happen.