What are painting & digging?
They are approaches taken in final stages of polish, or brillianteering. Painting shifts upper/lower girdle facets toward the mains so angles are closer together. The result is that average girdle thickness where the half junctions meet is greater than average thickness where the mains meet (diagram below). Digging tilts upper/lower girdle facets away from mains so angles are farther apart. The result is that average girdle thickness where the half junctions meet is thinner than average thickness where the mains meet (diagram below).