Halo

[Herb]

Dwight, I'm not really sure what you mean by 'halo' effect but I think you mean the slight difference in bluing near the numbers and proof marks. I think this is caused by the stamping, or rolling, of the numbers into the steel thereby displacing the metal and causing a molecular density in the immediate area different than the rest of the steel. This density would affect the porosity of the steel and the bluing salts or chemicals would not penetrate the steel as deeply as the areas away from the stamp causing the 'halo' effect. This is pure speculation but it sounds good to me. LOL.