20 Pieces of Octagon Flat Back Sew On Acrylic (plastic) Rhinestones, Size: Size: 18x25mm or about 11/16" x 1". These jewels have 2 holes for sewing that are about 1mm in diamater. Perfect for jewelry making, fabric embellishments, garments, Costume making, cosplays, clothes and shoes. All of these gems have silver flat back foil (non see through) except black that is opaque (full black covered). Make sure to check out our store Allstarco USA, we have over 2000 of beautiful acrylic gems in different sizes and shapes, from Tiny 1.5mm up to HUGE 60mm. Your best source of making your DIY projects! Acrylic 18x25mm sew on octagon jewels are 11/16" x 1". These jewels have 2 holes for sewing that are about 1mm in diamater. Perfect for jewelry making, fabric embellishments, garments, Costume making, cosplays, clothes and shoes. All of these gems have silver flat back foil (non see through) except black that is opaque (full black covered).