Shellac buttons; on the left is Dark Jethwa, right Kusmi #1. The seal impressed into the Kusmi buttons reads:
Holding any of the buttons to the light shows the large amount of impurities present, which I find one of the charms of Button-Lac. The colors are concentrated as are the buttons; in use the color is much more subtle. More on shellac, and a picture of Kusmi #2 buttons, here.