Ajax Electra

The Ajax Electra is one of the few detectors made mainly for gemstone prospecting rather than metals. It uses two long-range detection systems with transceiver and high-gain antennas to search for signals from stones such as diamond, emerald, ruby, tourmaline, garnet, zircon, quartz, topaz and amethyst, as well as meteorites. It suits gemstone miners and prospectors in mineral-rich regions. It is best used across open ground and old mining areas.

Results are shown on a 5-inch colour screen that Ajax says stays readable in bright sun and low light, and alerts change tone as you move closer to the signal. The device stores up to 1000 scans in 1 GB of memory, offers a menu in eight languages, and runs about 10 hours on its 7.4 V rechargeable battery. The packed kit weighs around 4 kg.

The manufacturer rates the Electra for a forward distance of up to 2850 metres and depth of up to 100 metres. These are Ajax's own figures, not a promise of results; long-range readings depend on the deposit, ground and operator, and should be followed up with geological checks before any excavation. The Electra carries a two-year manufacturer warranty. Buyers should treat it as a survey tool that guides where to look.