The gold on this frame is not masked off. It is drawn on by hand, and it has to be, because the alternative looks wrong.
The temptation with a two-colour finish is to tape a line and fill to it. Do that on a carved edge and the gold sits at a uniform width all the way along - which is exactly what a curve does not want. A scroll that swells and narrows needs its highlight to swell and narrow with it, wider where the form turns toward the light and thinner where it rolls away.
So our artisans lay the ivory first over the whole piece, and then work the gold last with a fine brush, following the highest ridge of each element by eye. Where the carving is bold the line runs generous; where it tapers to a point the gold tapers with it and stops just short of the tip.
Stand back and you do not see gold edges at all. You see a carved shape that appears to be lit from one side - which is the entire trick of a white and gold finish, and the reason it cannot be done with tape.