That's not fair. You're the expert.
I was totally shocked at the results.
I tried every setting I could on my F75 and at about the best I could do was get some kind of a beep with the coil rubbing the ring.
Try a small (or medium) size real gold cross. The 'X' pattern somewhat produces the same resultant........and nearly cancels out; subsequently making the target nearly undetectable.
Re-solder/Complete the circle of that broken ring...........and the F75 LTD will acquire it well beyond a foot.