Black Square 11/16" Corozo Button, Five Squares Tagua Nut "Vegetable Ivory", 17mm #SK-521
Square button with four square holes. It's almost 1/8" thick and slightly raised - 'pillowed' in the center. The back is flat. Silky finish with a bit of sheen, rich true black sustainable corozo/tagua nut. Sold per button.
11/16" Diameter/17mm. Also available smaller, 9/16", in a separate listing. They match.
...and in other colors in other listings.
Vegetable Ivory/Tagua/Corozo: has been used for making buttons since the 1880's, before plastic. It carves and dyes very well, is extremely durable, and looks better than plastic; not as shiny. Machine wash and dry, but not hot.