Color Zoning is a visible change in color within a single crystal or nodule, arranged in bands, cores, or growth zones. It forms as chemistry changes during growth or as impurities vary over time. Collectors use color zoning to read growth history, to orient cuts for display, and to document natural variation. Zoning can also help flag material that looks artificially uniform from dyeing.
To document Color Zoning, photograph the specimen in even light and include a close shot that shows boundaries clearly. Note whether the zones follow crystal faces (growth zoning) or crosscut the piece (possible alteration or staining). If you cut or trim the specimen, preserve at least one face that keeps the zoning pattern intact for records. Record zoning alongside transparency and inclusions because those often control how visible zoning is in hand specimen.
Color Zoning vs. surface staining Staining often sits on the surface or in cracks. Zoning is internal and follows growth-related patterns.
Color Zoning vs. banding in host rock Rock banding is layering of the matrix. Zoning is within a single crystal or mineral mass.
Color Zoning vs. dyeing Dyed pieces can look unnaturally uniform or bleed along fractures. Natural zoning often grades or follows crystal geometry.
Color Zoning vs. shadow gradients Lighting can create false “zones.” Check under even light and rotate the specimen.