This button is made of clear glass but looks golden because the back of the button has been painted. A curved V-shaped indentation has been pressed into the button and has been over-painted gold. Depending on the light, the glass sometimes looks like amber.
It's not a perfect circle which makes me think it was formed by stamping the v-shape into a blob of glass. The metal shank firmly glued to the back has got something like "Darian G.F.D." stamped into the metal.
