Hi everyone. This thread might be a bit old, but I wanted to share my own experience. Hopefully, someone out there finds it useful.
I use copper dowsing rods for the exact same thing: tracking down gold bearing quartz veins here in Sudan, specifically across the Nubian Desert and the Eastern Hills. These areas are famous for their gold deposits.
My setup consists of copper rods with hollow handles. In my experience, using them without a sample of what you're actually looking for doesn't really work. The main issue is interference from sulfides and iron oxides in the ground, which throws the rods off. To filter that out, I place small samples of those same sulfides and iron oxides inside the handles so the rods 'ignore' them. This trick has made finding gold veins much easier, though the yield is usually pretty low.
The latest tweak I’m testing out is wrapping the handles and about half the length of the rods in standard kitchen aluminum foil. I’ve been told this lowers the sensitivity so the rods only react to veins with a much higher gold concentration.
Once I finish the current dig and see what’s down there, I’ll come back here to post the results. Wish me luck!