Spoiler warn: there isn't a common ‘most effective metal detector for gold’. (Even though the GPZ 7000 is shut for those of you who will afford a detector that’s exactly the same cost as an automobile). The MINELAB Gold Monster 1000 at 45kHz represents the gold regular for sensitivity, although https://castocus.com/blogs/45741/Best-Guide-to-Metal-and-Gold-Detectors