I purchased a 10mm Black Sea Cultured Single Pearl Pendant in 18K White Gold from one of the most well-known names in the Pearl industry 20 years ago. My wife wears the pearl frequently. She does not use any makeup, but also does not clean the pearl after using it. She places it in a drawer with other pearls purchased from the same vendor. She recently noticed that the pearl had lost its luster so I sent it back to the vendor, thinking they would replace it. Instead, I was told that it could not be repaired and they would be willing to replace it at a cost to me equal to a discount of 25% off the current retail price. Am I being treated fairly or not?