This silver heart is about 18mm at the widest point, less than 3/4 inch, with a soldered shank. They have been stamped and antiqued. The work is very fine.
Some of the buttons have begun to oxidize and I think they may be German Silver. (The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel or German silver is named for its silvery appearance, but it contains no elemental silver unless plated. The name "German silver" refers to its development by 19th-century German metalworkers.)
Found at the estate sale of a seamstress, there were many boxes of silver buttons from Austria. There were several invoice and stamped packages dating from the late 1960s to the early 1970s.