There are metal detectors that are specifically designed to sweep search for gold. Gold metal detectors work on the principle of cancelling out mineralization, so whenever you find a metal detector specifically for gold, look for the ground balance. The ground balance feature in the metal detector cancels out detecting minerals in the soil and focuses on finding the metallic objects beneath that are unnatural to the soil.

As far as gold metal detectors go (although they might not be exclusive) they work on two principles; VLF and PI.

do check for the size of the searching coil, as smaller search coils are less sensitive to small pieces of gold as compared to the metal detectors that have large searching coils. Pulse induction metal detector are newer technology that work by sending short pulses of one type of polarity. When the search coil is encountered with a metal object (of an opposite polarity) the pulse indication detector sets off sensing the opposite polarity, sends the signal to the receiver circuit.

Gold metal detectors can detect gold as small as the size of the grain and as big as an average nugget. The principle is that the gold as small as the size of grain is easier to find in the shallow depth (of 1 or 2 inches maybe) whereas, gold portions of the size of nugget can be search scanned at the depths of 1 to 2 feet.

Some metal detectors have the ability to find common trash items such as iron and stainless steel. Pulse detectors cannot filter out trash items.

Some of the popular choices for gold metal detectors include; Garrett GI 2500 metal detector, Marko Geotech, DRS electronics proradar X5 system, XP DEUS goldfield program etc. You can also look online for comparisons and reviews of several metal detectors that are projected to be good gold finders.