These are the earrings and necklace that she always considered a “set”, she has also a graduated strand of white pearls with the same background story, exact same clasp but no M marks either
This is about the first brooch....of Bab4444..... I have seen some fakes and need to get my frustration out! So many "famous" jewelry is copied and it has been done as far back as ancient Egypt & Rome. My guess is that this Bab444 brooch is a copy. One thing to think about is that in the 1930-40's in the US there was lots of copies of jewelry, especially brooches and patents were starting to be used on jewelry. This idea of patenting or signing seemed to take a while to make the rounds to other countries. K. Mikimoto was very early to realize that signing jewelry was important. But there have always been the tendency to for jewelers to copy each other when a design catches on. We still have this today with China selling "famous" Trifari brooches on Temu & Alibaba...They look close, but the signature is not quite as crisp and clean as it should be. There is also a tradition in Mexico of copied jewelry in silver. A year ago I was researching Tiffany silver and found on Etsy Shops (based in China) selling Tiffany silver designs with the same marketing as Tiffany: Handmade, high quality.
A note: Silver 925 will turn bright blue with 18k acid...so it is testing 925. Most Mikimoto brooches of that era were Rhodium plated..so they don't test 925.