To the best of my knowledge after some research, this coin is most likely not a silver proof but a composition of Copper-Nickel.

I was able to narrow this down with a few clues seen on the coins obverse which shows a young bust, the "19" date below it, and a partial "C" to the upper left of of her head- If the coin were silver, the word "Silver" would be in that spot. By measuring the diameter and thickness of the coin, the .925 coins measure 38.61 mm and the copper nickel coins are 38.8 mm.

This listed coin turned pendant has a diameter of 38.8mm 

Thickness of this cut coin pendant is 2.7 mm- the mintage I suspect this coin is should be 2.75 mm, however the cutting process could have thinned out the coin slightly.

There isn't an indication of what artist cut this coin but it is clear that the intention was to showcase the birds on the reverse of the coin. You can see in the photos that this took a trained eye and a steady hand as the artist did a excellent job removing all font from the reverse with only the birds being present.