Accent designs with dark color using the smoky quartz 12mm coin beads from Dakota Stones. Available by the strand, these gemstone beads feature a circular coin shape. These beads would look excellent in a bracelet or necklace design. Smoky quartz is named after its smoky color, which is caused by gamma rays. The color of smoky quartz ranges from brown to black and sometimes smoky gray. Mined in Brazil, the stone is believed to enhance organizational skills, making it good to have around the workplace or home office.