Stag grips are very tricky to make. One must start with a piece of antler only slightly larger in diameter than the finished grip circumference. If the section of antler has to be whittled down too much to fit the grip frame, the top 1/4" or so of solid bone is penetrated exposing the more porous inner area with the former blood capillaries. That is the 'speckled pattern' referred to. It is naturally dark, easily fills with dark colored polishing compound, and grime, turning blackish. The best polishing compounds are creamy white to match the natural stag color.
Making premium stag grips in the old days wasted much of the antler to avoid it. With current prices of real stag, much waste is unacceptable. Therefore current grips with exposed inner core are much more prevalent. It's even more difficult to avoid with elk antler which is inferior to stag.
The gold color comes from age, human hand oils and handling, a sort of patina that's not very deep. Some like it, as in aged ivory. But stag can be restored/re-polished to remove surface checking and reveal the original creamy white color as you observed on this pair of grips.
