This is likely the Mikimoto Black Pearl Étrenne, Étrenne Noire. It will be given to you in a regular Mikimoto necklace blue hard case, as the round case is not available. The string was replaced and it underwent paid cleaning in 2020. The engraving is on the inside of the clasp insertion, so I couldn't get a good photo, but the engraving is definitely there. The Étrenne Noire doesn't seem to be sold anymore, but it was apparently sold for 1.1 million yen a few years ago. Necklace K18WG Pearl: approx. 9-11mm diameter Earrings K18WG Pearl: approx. 9.3mm diameter