Meno your story reminds me of when I lost a stone from my engagement ring. It is a diamond flanked by two sapphires. It was a 70s style with a high setting and I was always having to get it repaired. The last time the jeweller repaired it, he said it would be almost impossible to match the sapphires if I ever lost one.
It was my birthday and I went to pick up a takeaway. As I came out the shop, I noticed one of the sapphires was missing. My daughter and I searched all out of the shop, my car, the driveway etc. and no stone. I was distraught.
A colleague had given me a bottle of cava as a birthday present, so I decided to drink it. The next morning, I was putting the bottle in the recycling bin and the sapphire was stuck to the bottle. . How it got there, I don't know. The only thing I can think of, is that when my friend gave me the gift, the stone fell into the gift bag.
I too got a new setting, to make sure I didn't lose it again.