Minelabs aren't sensitive to thin gold chains or small gold earings like some other machines are, but in terms of even the thinnest of gold rings, being an intact loop, it'll bang as deep as an old silver coin on a gold ring. I tested this with a woman's gold ring. Same sensitivity and all other settings. This video demonstrates...
http://youtu.be/G817__EOC8A
The video is mainly about PP versus disc and high vs low volume on both to see any potential impacts of that in both modes to contrast to each other, but the video notes the gold ring vs clad dime thing and also the video description below it goes further into that.
Note the gold ring got more depth than a clad dime. Why? Because the ring is bigger in diameter, and even though it's hollow in the middle unlike a coin the intact loop produces a large image to the detection field.
I also am also finished editing another video to demonstrate this. This type using a foil drink top versus a clad dime. Both videos should prove that low conductivity is not an issue for the BBS units. They treat them just like high conductors due to the multifrequency lighting up all low, mid, and high conductors well. It's the physical image of mass that makes then less or more sensitivity to the BBS units. Thin gold chains are not an intact loop (no physical connections), and so those and tiny gold earrings are what the BBS units (like the FBS units) suffer with.
You can look at this as a plus or a minus. I look at it as a plus. I've owned machines sensitivity to fine gold and they made for a bumpy ride on land having me chasing small foil flakes that sounded good. I want stuff like that to sound sick so I know what it is. On the beach, way I look at it most gold lost is in the form of rings, so I only want best depth on those (IE: Sovereign GT).
I do plan to pick up an AT Pro for re-gridding water or dry sand after I got all the deep stuff with the GT, so I can scoop up any tiny earrings or thin gold chains after I cleaned the area with my GT. The AT Pro isn't said to be as sensitivity to fine gold as say a Tesoro, but just the same it looks to be a good bit more sensitive to that stuff than a Minelab. Good enough for me, for a backup unit at it's price, that I can use in land/water at the beach like my GT, and also on land in heavy trash when I'm in the mood to swing faster without as much risk of masking in heavy trash.
Most days I prefer to move slow though at "dead" sites and feel that gives me better ability to fish out some keepers in iron or trash, but also I'll use the AT Pro for a faster woods scouter where I can come back later with the GT to work a site more thoroughly. At just over $500 for a land/water unit how can I go wrong is the way I look at it? Also for rainy days when I don't want to risk using GT even with plastic bags over meter and control box. Many Minelab guys have AT Pros as back up units on land for heavy trash when they just want to move faster that day, although I can roam pretty fast with the 12x10 on my GT in my soil/sands without worries of depth loss or masking so much.