The Tiffany dynasty was founded in 1837 at 259 Broadway in New York City by Charles Louis Tiffany and partner John B Young. In 1847 they expanded and moved to 271 Broadway, it is here that American made silver finally took its place alongside the Tiffany name. John C Moore a very talented local siversmith played a major role in this development. The firm moved yet again in 1853, to larger quarters at 550 Broadway and the name was changed to that of which it is known today Tiffany & Co. In 1867, they exhibited at the Exposition Universelle in Paris, where Tiffany became the first American firm to win an award for excellence in silver. In 1868 Charles L. Tiffany amalgamated with the Silversmith firm Edward C. Moore ( Johns son ) and consequently became a manufacturer of silver as well as a retailer.By the time Edward C. Moores death in 1891, Tiffany & Co. had won major awards at  successive European and American Expositions and had become the most internationally respected American silver manufacturer. The founder Charles L. Tiffany passed away in 1902. Tiffany &  Co. moved to its present premises at 5th. Avenue in 1940 and remained in the hands of Tiffany and Moore  families until 1955. Tiffany & Co. continues the legacy of producing some of the worlds finest designs and quality in silver.

After the Moore silversmithing firm was absorbed into Tiffany & Co. ( 1868 ) and Tiffany began its own production of its own silverware it became the tradition to mark each piece with the initial of the Artistic director or President of the firm. this practice continued until the mid 1960s.

Conclusion: Looking from right to left.

1) The name Tiffany & Co. is the logo since 1853 to this present day.

2) 19750 is the pattern number. 1920 pattern nr. 19683 - 1921 pattern nr. 19831.

3) 373 is the order number.

4) In 1851 seeking to give their silver goods distinction, Tiffany became the first American firm to use the English Sterling 925/1000.

5) M this was the initial of the Artistic Director at the time John C. Moore 2nd.Directorship between 1907 - 1947.

Summary:

This is a hallmark of a piece of sterling silver made by Tiffany & Co.in New York City, under the directorship of John C. Moore 2nd. in 1921.