female hand use tweezer for calibrate the specific gravity precious stone for separate the type of stone with the hydrostatic

balance bright buyer calibrate calibration calicrate calipers certification classification cut dense density diamond different equipment examine expensive experiment expert facet female gemologist gemology gems glass gravity hand hydrostatic industrial industry inspector jeweler jewelry lab laboratory loupe measurement metering object people polariscope precious reflection refractometer science semiprecious separate shiny specific stone stones technology temperature tweezer tweezers type use weighing weight