Coffee brown studs with a marbled pattern and a matte opaque finish. These are part of the 'Retro Button Stud' line & it comes in loads of colors & sizes. This one measures about 20mm or just over 3/4" in diameter. The model is wearing this size & shape in a Blue Bullseye colorway so you can get an idea of the size & scale when you wear them.
Most all earrings are made with vintage lucite parts that were made in Rhode Island in the 1960's - early 80's by Best Plastics. We hand-set them with surgical steel earring posts and they have sturdy surgical steel/acrylic backings on them as well. Light-weight & fun to wear.