They look a lot like my grandmother's Richelieu pearls from the 1930s.
By the way, the Wikipedia entry for Richelieu pearls is completely WRONG. The Wiki entry makes it sound like Richelieu were cultured pearls. They were imitation pearls that never saw an oyster. Richelieu pearls were plastic coated with fish scale slurry. My grandmother's are ivory colored and do not have any overtones. I'm not sure if they have yellowed over the years, or if they were originally ivory colored. They have a sterling silver clasp.
According to my grandmother, "They were the best pearl that was not a pearl." She gave them to me, when I was 11, because she knew I loved pearls. My heart sank when she said they were imitation, and I never wore them. Fast forward 40 years and I polished the sterling silver clasp and restrung them and they're not bad looking, as long as I don't put them next to my real pearls. I enjoy wearing them every so often. They have a very Queen Elizabeth II look to them.