I have a pair of white gold/diamond snowflakes earrings. Mark

Hi. I have a pair of snowflake diamond pierced earrings. White gold. So pretty. I don't understand the marking on back. K18.375. Any help would be appreciated. Thankyou for your service. Also, I have a platinum diamond possibly art deco Nicolet watch I am trying to value. Do you offer help with that, also? Thanks. Mary