Are these genuine Mikimotos and approximate value?

by Dave Kowalski
(Massachusetts)

These were left to me by my grandmother. An old flame got them for her as gift during thr Korean War. They are in a Red Box. The satin lined lid says K. Mikimoto, Inc. Pearl Island TOBA. They are 24" long with the largest pearl (7mm) at the center and getting smaller towards each end - each end in the 3-4mm range. The clasp hook says 14K with what looks like a shell in front of it. The larger part of the clasp is white gold. I can't distinguish any initials, etc on it. It has almost a zig-zag pattern on it that overlaps in the center. Any clues? Thank you!