These are 4x4mm cubes, but drilled from corner to opposite corner, making them 6mm long. Amethyst is a beautiful purple stone, known as a "Gem of Fire" by ancient cultures. It has been greatly sought after throughout history and was at times valued as highly as Diamond. Today, this semi to precious variety of quartz is found in many locations around the world. The presence of Manganese within the stone produces the purple hue, and variation of the amount of iron in the stone creates a color range from reddish purple to deep violet to light lilac. The name derives from the Greek word for "not intoxicated" and was once believed to prevent drunkenness and overindulgence. Maybe because you had no money left over for wine? Worth it, I say. 6mm x 4mm Approx. 52 on approx. 16 inch (40.64 cm) strand. (strand)