I lost a baguette from my first engagement ring but it had a warranty and was replaced by the store. I have also lost diamonds from earrings that I never found again and didn’t have replaced. A piece opal set on some sort of backing fell out of a beautiful necklace once. I was heartbroken that it was lost but found the piece when cleaning the bathroom counter. I didn’t immediately recognize it because it was upside down. My most heartbreaking loss of jewelry, though, was a jade dolphin charm for a necklace. I participated in an outdoor survival class and when I returned to our office after, the chain was hanging open around my neck. That one was a gift from my mother and I wore it constantly. I hope you find an economical solution for replacing your diamond!