Beautiful velvet matte finish, almost like suede. Dark navy / indigo almost looks black in some low light, high quality. Large button is 28mm/ 1-1/8" diameter, or slightly less.  It's not quite 1/16" thick. Just enough of the natural shell's glow comes through to create slight iridescence and some variance. (Clearly these are not plastic buttons!)  Smooth but not shiny. For your best uses; agoya shell is renowned for its strength and beauty. The backs are mottled black shell.  

This is for the large 1-1/8" size, 28mm. For $2.60 each.

We also have this button in 5/8" in another listing; see item # 1209.

And 3/4" in another listing; see item # 1208