Folks --
I do not think Flintstone is referring to a Gold Bug Pro, when he is talking VDI 10 being a 14K ring. A 10 is WAAY too low for a gold ring, of ANY size, on a Gold Bug Pro, and PLUS, he said himself that "it's been a few years." The Gold Bug Pro/G2 are not "a few years" old, so no way is he referring to one of these. I think it is safe to say that there is 99.9 percent chance that all gold jewelry should hit above 30, and similarly, that maybe 95 percent will hit above 40 (unless it is something like a single link broken off of a gold bracelet, etc.)
I have dug tiny, tiny bits of metal, etc. with this machine, so I have gained a halfway decent feel for what shows up in that 40-50 range. I have not dug any small/tiny gold yet; having said that, EVERYTHING I dig in the 40s has been a tiny little shard (like bird shot size) of something metal, or else small bits or flat pieces of foil, or very small can slaw. I ABSOLUTELY agree with those here who say that thin gold chains, earrings or earring backings, etc. can hit in the 40s. Makes total sense to me. I think very few gold rings, except very, very small ones, would hit below 50. My men's band hits at 70, FWIW. If you want to hit ALL gold (I'm NOT talking tiny nuggets or flakes, i.e. placer gold -- I need to do testing on small "raw" gold; I'm talking here about "jewelry" gold), I think you can dig only stuff above 40, and feel pretty confident that you will not miss much of anything (there should not be much which might come in below 40). If you want to dig only rings, or chain/bracelet pendants, you could probably focus above about 50, and then you'd only be missing some small earrings, backs of earrings, thin or "link-type" bracelets and chains, etc. MAYBE a small, thin child's or woman's ring. Yes, it could be something "substantial" (especially the bracelets/chains), but you'd still get most rings. I would not personally want to ignore anything above 50, if I wanted to find gold, unless I was specifcally focused on finding only the larger rings and other similar size/mass jewelry pieces.
But in the 40s? If you want to find most all jewelry gold, I think you would miss some stuff in the 40-50 range. ESPECIALLY the 45 to 50 range.
Just my two cents.
Steve