[USA] These pieces were gifted to me by my later grandmother two decades ago. She called them “costume jewelry.” Does anyone have any information about them?

I believe the clear stones on the ring are diamonds based on how they were cut. I don’t see any marking indicating whether the ring is gold or not.

The flower pendant is sterling silver.

The circular pendant has no information that I can see about its composition, I don’t think it’s gold. Curious about its origins nonetheless.