Huge Seafoam Green and Black Bicone Agate BeadsPrice is for 16. 5 inches of these knotted agate beads. Each bead measures 20mm x 18mm and about 18 beads in a string. Hole size is 2mm. Few of the beads has a druzy hole. These beads are dyed to have the green colour but the colour does not come off. Agate is one of the most common bead beaders use because it is readily available in an abundance of styles and shapes. What is agate? Agate is a variety of microcrystalline quartz that forms in layers