21/ Understanding the Gold Signal
Compared to the challenge of  finding gold jewelry at inland sites–coins are easy.  For one thing, as you go further up the conductivity scale, there are fewer targets–not so with the middle range.  Also, as the price of gold has risen, there is less around.  However, the amount of trash  in the ground is still the same.  This means that it’s necessary for the gold hunter to have a very solid understanding of just what kind of signal he or she is looking for.
Coin signals are pretty specific–a round high conductor.  Because many coins contain metals that blend with the ground–corrode, coin signals can have what I’ll call “infinite” characteristics.  By “infinite” I mean those signals that can’t be distinguished from the ground all that readily.  They may resister partly as low iron–because they are rusting.  They may resister partly as being too big or overloads.  This is true of any object that contains steel or corroding metals.  These metals include nickel, tin, brass, bronze, and low-grade aluminum.  I mention this because gold is the opposite.  It doesn’t corrode at all (the exception would be very poor quality 9 karat that’s been in the ground a really long time), and presents a narrow, distinct (in electrical terms) response.  This response can come in anywhere from down into the foil range (with some important differences that will be discussed below) up to just below where a quarter would come in.  While there is certainly big gold around, as a generality, this should always form a solid upper cut-off in your signal selection.  As touched on above the simplest way to describe the gold signal–that should inform your dig choices constantly is that it’s “a very good signal”.  That does not necessarily mean that gold is big loud signal–because that often means a high conductor.  Instead, what we are talking about is a clean, even tone.  This is where object shape and coil control come into play as well.  Some misshapen objects such as bracelets, crucifix pendants, odd shaped earrings may give off a broken signal but it will still have overall good characteristics.  Sweeping fast over an object fast may cause it to give an uneven signal.  What you won’t hear is a rough, broken signal.
Another difference between any object that rusts or corrodes and a gold target is that gold has exceptional consistency.  With many detectors, the way to tell gold from foil is to speed up the sweep.  Because foil is such a low conductor, it’s much closer to the ground’s signal and therefore does not stand out as much–the signal breaks up.  With gold, the response becomes sharper.
Another gold signal characteristic is that because it’s such a good conductor, the signal “carries” well.  I mention this here to emphasize how important it is to bench test your detector so that you know just how deep it goes in each mode. This way you can not only tell how deep an object is, but also how good of a response it is for it’s size–that is how well it’s coming to the surface from the depth that its sitting at. Gold is also recognizable in this way—especially when it’s deeply buried.
My more general point is that because gold is such a good conductor there is an array of resultant signal characteristics to recognize it by.  These may not evident one by one–but in combination–as a group of signal characteristics they give you a pretty good idea as to what you are looking for.  Also, I purposely avoid mentioning any detector types or brands in this discussion–because these signal characteristics are universal–and can be observed with any machine–from the $60 “stick-beeper” from Wal-Mart, up to the state-of-the-art unit.  The importance of recognizing these basic signal characteristics far outweighs the value of any detector target “ID” system.
So what you have is a much more precise set of characteristics than a coin would present.  However, these characteristics may come in at a wide range of the conductive scale.  Let’s list these characteristics for clarity:
•    -a  narrow response on the ID scale–not jumping around (coil control notwithstanding).  The polar opposite would be something like a bottlecap that’s alloyed with multiple metals.
•    -a clean, distinct response.
•    -in audio terms, a sharp response.
•    -not usually broken but may be uneven (coil control notwithstanding).
•    -good “carry”–strong even though small and / or at depth.
•    -repeatable
•    -usually round or at least sounding about the same from any direction–sweep speed notwithstanding.
•    -finally, in all-metal mode, we are looking for a signal that response “under the coil” that is something that is not a long drawn out response.  (More on this under “Coil Control and Gold” below).
From “The Gold Jewelry Hunter’s Handbook”
by clive james clynick.