The only thing TID can tell for certain but not 100%, are pennies, nickels, dimes and quarters. Basically because they all are the same size and composition. Copper & zinc pennies will ring up different but you'll learn the difference. All silver coins will also have their own range. Other than that, its a crap shoot on gold. Due to soo many shapes, sizes, karat variables, it can come in anywhere. Couple of years ago I was hunting a beach and expected to see a zinc penny in my scoop. I was in total shock when there was a 22k humungous gold wedding band. I almost didnt dig it cause of the TID number. Been a beach hunter for over 20 years now, Never had a meter on any beach machine. Just dug anything that beeped. Now there are machines with meters that work in the wet, salt sand. Always trying to guess what's in the scoop. I, too am guilty of passing on the zinc.
In fact, last night, I ran into an area of zinc;s and didnt dig. Then I got a higher number zinc and decided to confirm it was a zinc. At first I thought, I just found my first gold ring with my new Deus 2.
As I was walking down the beach afterwards, I kept saying awfully high number for a gold ring. Only rings Ive found with zinc readings are high karat or extra large. Sure enough when I got back to the car, the ring was a POC !!!!
Like someone said, location, location, location. Much easier to dig everything at the beach than all the can slaw in the parks !!!!
In my 1st 18 months of detecting on land, I dug 10 pieces of gold. I dug that many in less than a month at the beach. But that was way back when gold was $300 oz and everyone could afford to buy real gold. Not the fake crap they sell today.
Want to find gold, Find a beach !!!!
HH
Donna(NJ)