Turn your jewelry into one-of-a-kind wonders with the yellow opal 15x20-20x25mm slab beads. Opal is a stone formed millions of years ago by a combination of silica and water that flowed into cracks and spaces in the ground and then gradually solidified. Ancient Romans associated the opal with hope and good luck. You'll love the unique shape of these beads. They're sure to enhance the style of any jewelry project. Gemstone beads are the perfect way to add natural beauty to your jewelry designs. Since gemstones are formed naturally, each bead is a unique treasure. These gorgeous gemstone beads are available by the strand, so you'll have plenty to work with.