Geophysical techniques are effective in diamond exploration. They can in most cases accurately detect and map kimberlite and lamproite pipes, whether diatreme or crater fades, and may discriminate separate intrusive phases within an intrusion. The most cost-effective geophysical reconnaissance technique has been airborne magnetics. With evidence that a major contribution to kimberlite and lamproite magnetic anomalies is often remanent magnetisation, local anomalies may be of normal or reversed polarity compared to a non-magnetic background. It is common that Australian and Canadian lamproites and kimberlites have reversed magnetic polarity. Many South African kimberlites are however of Triassic to Cretaceous age, which coincides with a long period of mostly normal polarity, and hence these kimberlites would be of normal polarity even if remanence was predominant.Airborne electromagnetics (AEM) is extensively used in diamond exploration. While its cost is a factor of three greater than magnetics, it is particularly effective in detection of weathered or crater facies pipes. AEM assists selection of targets for ground follow-up in areas where kimberlite magnetic anomalies are small. It is also useful to discriminate targets where other sources of localised magnetic anomalies are common. Complementary surface mapping tools (for example airborne radiometrics, aerial photography, digital topography) have all been of assistance in the exploration process.Detailed ground geophysics can usually map out the surface extent of kimberlite or lamproite pipes, and may identify separate intrusions within one kimberlite or lamproite. Since separate intrusions may have very different diamond grades, this is of significant importance in the location of initial geological sampling. Ground magnetics together with either electromagnetics or resistivity are recommended for detailed mapping and multiple intrusion recognition over a potential kimberlite or lamproite. Seismic refraction and reflection may provide useful and accurate data but at a significant cost that is not usually justifiable in routine exploration. Determination of geometry, such as subsurface pipe shape or depth to top, may be possible in certain circumstances.