Silver Trumpet Vase

My mother was given this vase in the late 1930’s by a college professor/mentor of hers. I am hoping to find some information from the engravings on the bottom. It appears to be embossed with a R and a B, then underneath that, the word sterling, then, below that it reads, reinforced with cement and then the numerals 1 2. Thank you for any help you might be able to offer.