Is PT900 Platinum? Understanding Jewelry Markings & Value

Question
I bought a platinum wedding set 4 years ago from Zales.  Today I took it to have it looked at and possibly sell it.  They offered me a very low price saying that it is not platinum because it was marked PT900 ODI and not PLAT.  I have never seen  platinum stamped PLAT before.  Please tell me what you think.  The ring has a half karat marquis diamond.

Answer
Dear Stephanie,

Lesson learned - stay away from mall jewelers and go to "Mom and Pop" stores - privately owned jewelers - you will invariably find them far more knowledgeable and competitively priced. Zale needs to operate hundreds of stores and pay huge rents in malls. The variable quality of their training and staffing and the mark-ups they need to maintain to pay those rents are the result.

Your ring is platinum. "PT900" indicates that the platinum alloy is 90% platinum. "ODI" was the company from which Zale's bought the ring.

Trying to sell a ring on your own is very will be challenging. There is not much demand for marquise diamonds today. And a small one (under a full carat) will not appeal to many jewelers. You may get less than 1/3 of what you paid at Zale's. Get  out of the mall and try a number of private jewelers and pawn shops. Ask them to please write their offer on their business card as you are comparing offers store-to-store. If you must sell, just go back to the highest bidder.

Best of luck,

         Rich