Discolored Platinum Engagement Ring: Causes & Solutions

Question
My finance gave me a engagement ring with a six prong Coast platinum bezel diamond setting in September. He got the diamond at a different store and they set it there. I have recently noticed that the base of the prongs were turning a yellow cast. I brought it back to the place he bought the setting and their jeweler said that a white gold solder was used and said that since I had the diamond set somewhere else, they are not responsible. My diamond jeweler said otherwise, that the soldering was done only at the time of manufacturing. But they dipped in in Rhodium to help.
What is the process of putting in a diamond, is soldering done? I want to get to the root of the problem, I was sold a platinum ring so why is white gold solder used? I wanted to have some knowledge of this process before I go back to the setting store, it is not good business practice to be deceitful.

Thank you,
Karie

Answer
This is a normal problem with Platinum.  You cant' easily solder with platinum because it gets to hot for any stone even diamond. If you had the crown changed to set the diamond they had to use white gold to solder the new crown in place. Unless they used a Laser ( I do ) The manufacturer always solders in the crown before any stones are set as not to have that problem.  Coast is considered a good quality manufacturer,  I would call them they are based in LA
Get the facts.  I don't know here you are but try and find some one that does Laser repair.  They can clean off the gold solder and clean it up to remove the solder.  Sometimes it can contaminate the metal.  I would get the facts from the manufacturer.  Rhodium Plating is a good easy solution to your problem.