All gold detectors are based on the same technology. Of course there are different types and models but they are all variations of the same electromagnetic technology. A magnetic field is created inside the gold detector that reacts with the magnetic field of a metal on the ground. The metal detector has the ability to convert this reaction into a signal that tells you that metal has been found on the ground.

The most important aspect of gold detectors is tuning. You have to carefully calibrate the gold detector to properly receive the signals from the ground, depending on what you are searching for. Often, this process must be performed (usually by pressing a button) every few minutes depending on the gold detector type.

Another important factor is motion. Some gold detectors require a fairly slow swinging action while others need a much quicker action. For best results you have to use the speed which is considered as optimal by the manufacturer. Carefully read the gold detector's manual before performing any searches.

Last but not least, frequency. Most gold detectors operate in low signal frequencies between 5-10khz and 15-20khz. The reason for that is because low frequencies go deeper into the ground. If you are targeting objects like rings, coins or similar objects then low frequencies between 5-20Khz is what you need. Some multi-frequency gold detectors (which are very expensive) have appeared in the market the last few years, claiming advantages in gold detection and depth performance. In my opinion all these claims are overstated.

I've noticed that not a single gold detector manufacturer ever specify the detection depth of their machines. This is always confusing. The reason is that there are many things that affect the depth detection like the ground type, moisture etc. Gold detector manufacturers will not specify a specific depth range (eg. 10 meters) because another manufacturer will immediately specify a higher range (e.g. 11 meters). In my opinion gold detector depth range is almost the same for all brands of the same type.

Another half-truth is that the deeper you can go into the ground the more treasure you can find. I think that this is not the case. The deeper you go, the less you will find. If someone would burry a treasure 300 years ago how deep do you think he would dig? I think the average depth would be about 10 meters. Archeologists discovered treasures hidden for thousands of years, buried in the ground in less than 5 meters in depth.