These blue beauties are 8mm and I set them in 6 prong settings of .925 sterling silver. They are December birthstones - Blue Topaz - these are Swiss blue. Soothing and cool color. All of the metal is .925 sterling silver and is reclaimed/recycled. Please contact us anytime. Thank you for looking in! This will come to you gift wrapped with a signed studio card describing the materials. 100% of the revenue from your purchase will help to rescue and shelter special needs animals. Studio Cards, Swiss Blue Topaz, December Birthstone, 1 Day, Handmade Silver, Prong Setting, Blue Topaz, Sapphire Ring, Birthstone