This International Standard is applicable to high-purity germanium crystals used for radiation detectors for gamma-rays and X-rays. Such germanium is monocrystalline and has a net concentration of fewer than 1011 electrically active impurity centers per cm3, usually of the order of 1010 cm–3. This International Standard specifies terminology and test methods for measurements of basic characteristics of high-purity germanium crystals. These characteristics are net electrically active impurity concentrations (hereinafter (NA – ND)), deep-level impurity-centre concentration and crystallographic quality of crystals. These test methods are not mandatory but have found general use in the industry and provide verifiable and desired information to the detector manufacturer. Test methods for completed assembled germanium detectors are given in IEC 60973 and IEC 60759.