For the I.M.A.G.I.N.E. peace now project, we took apart a gun to make the Squash Blossom Necklace. Every piece of the firearm was disassembled and we were able to consider all of the shapes. With a large saw, we took the barrel and sawed it up. With just the cross-section of the barrel in front of us, we placed a large gemstone in the center. WOW it was a natural fit! Then- when measuring the stone for the mounting- we realized "OHHHHHH!!!! THAT is what 9mm means!!!! It is the inside diameter of the barrel!!" This comes in lab-created ruby, lab-created blue sapphire, and a lab-created padparadscha sapphire (orangish/ pink), all in sterling silver for 200-.