"Palladium Plus" High School Class Ring

Update: I saw a youtube video that said you can test palladium, by dropping 22k acid on it, and the liquid should turn a yellowish green. My ring passed. Most palladium is 950 pure, though some is also 900.
My ring is from 1980, before hallmarking was required on palladium. Newer palladium will have PD950 or PD900 marking, mine says simply palladium plus. Palladium is worth about $1000 per oz, so my 900 or 950 pure 9.1 gram ring is worth about $250-270 in precious metal content. Palladium is harder to sell than gold or silver, but it is valuable. It looks like platinum, but it is much lighter, about the same weight as 14k gold.

In the case of my palladium plus ring, I sold it a few years ago for about 90% of what I believed the palladium value to be. The buyer told me that when he had it melted, that he was told that it was less than 90% pure. (about 75% pure, IIRC)
I gave him back a portion of what he had paid, as I trusted him and had done other business with him before.