I am not sure. Howdy will have to verify this, but I believe that an undrilled core was used for the real 2.50 Pink. Drilled cores were used for the fakes. A drill hole would appear as a large black circle on an x-ray. See page 42, top photo of the altered x-ray at 6 o'clock. The wedge of brass was used to attempt to plug the drill hole. It does not appear on the x-ray of the original. I can't explain the black small circles on the "Altered" at 3, 9 & 12 (appear to be small drill holes) nor the white circles at 3, 6, 9 & 12 (appear to be extra brass as on the inserts) on the original. On an x-ray, harder substances such as metal, appear white and softer substances appear darker. Air, or a drill hole would appear black. Substances between "air" and "metal" appear as shades of gray. The harder or thicker the substance is, the lighter it will appear on the X-ray.