SUBJECT: (101) crystal plane in a natural, twinned, gem-quality diamond from Voorspoed, South Africa. Polishing exposes the twinning plane and cathodoluminescence (CL) imaging reveals the twinning plane, the twins, zoning and erratic growth.; CREDIT: Brooke Matat Jablon, University of Strathclyde; METHOD/INSTRUMENT: JEOL JXA-8530F field-emission EPMA