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. Assortment includes 42 grams of Half Pearlz in 3 sizes; 4mm, 5mm and 6mm in 12 assorted colors. Approximately 3.5 grams of each color.