African Green Opal Gemstone Beads 40mm Rectangle Approximate Size: 40mm long x 30mm wide x 7mm thick. Please note the image at left may be larger than life to help show the fine details. Strand lengths are approximately 16 inches long and each strand contains approximately 10 beads. Average strand weight approximately 115 grams. These African Green Opal rectangles display a unique, eye-catching mixture of earth tone jasper matrix embedded with green opal.