Flat Back Half Round Pearls in AB finish. What is AB finish? AB or Aurora Borealis is an iridescent finish that gives off a sublte shimmer. These craft embellishments are flat on the back and have a smooth round top. They can be easily glued onto most surfaces and are great for providing finishing touches to paper crafts, jewelry, nails, clothing, cell phone, accessories and many other crafts. These metallic pearls also make great filler for any shaker craft.