u/New-Republic-7864

Hello everyone! My mother gave me this pearl necklace a few years ago, and I just rediscovered it while clearing out some things. She can't remember if these are freshwater or saltwater pearls. Is there a pearl expert here who could help me identify them?
The clasp is stamped "375 JKa", which I believe indicates 9k gold . The necklace is 37 cm long. I am also looking for advice on how to properly clean and care for them. While I know I can search Google, I would love to get practical advice from fellow pearl owners who know exactly how to look after them.

Thanks in advance!