A Favorite Brooch

This is yet another that I found in my grandmother's stash. I know it's not diamonds, but have no idea about the metal. The baguette stones are a gorgeous cobalt blue. I don't know if they are sapphires or glass. In the right light, this thing will put your eyes out it's so bright! I would appreciate some help in identifying the maker. On the back, in the upper right corner is a capital "B". Does anyone know the maker and/or possible age of this piece. I'm guessing late 1800's, early 1900's. It is just over 1 3/4 inches long and almost 3/4 inches wide.