Reply To: What Instruments used to measure Girdle thickness & [W] Width of Stone? › Forums › Tools and Other Hardware › What Instruments used to measure Girdle thickness & [W] Width of Stone? › Reply To: What Instruments used to measure Girdle thickness & [W] Width of Stone? April 16, 2018 at 2:35 pm #4482 thomasreevesParticipant @thomasreeves Peak optical comparator is great for measuring the girdle as well as checking your meets. Several on that auction website for $ 15. range. I paid like 80 new for mine years ago after being recommended by Vern Johnson.