All buttons made by the firm of Leo Popper and Sons from New York City, USA were made before 1917.
They are multi coloured glass buttons mainly with a key shank. Many have embedded foil or tinsel spangles which give the extra sparkly irridescent look.
I have three small ones but this one is much larger at approx 2 cm. It is a new addition to my collection.
Reference: Big Book of Buttons, Page 214