Well,....hmmm. My best advice for you would be to get some gold rings of different types and see how each effects the M6's VID.
Bench test show me how each ring displays a different number on the VID. Most of the time it locks on a reading. Meaning the values don't bounce around like can-slaw does. However, if the ring is broke or bent, or even has a stone the readings can also bounce around I discovered. Put a piece of foil next to it and it reads like a piece of trash.....
The gold necklace I found yesterday was a solid +37. Another ring I have is +18 and I also found a antique gold wedding band that reads right there on the zinc penny range. The plain wedding band reads a nickle. In other words.....to find the gold that just might be in your path (if your so lucky) you have to dig all targets. Doesn't matter what brand or how expensive the machine is. If you want to find the gold expect to find a lot of trash too. If you want, you can ignore the high silver end of the range. But then you're going to ignore silver jewelry too. Which is a lot more common then gold.
And keep this in mind: 99% of this hobby is luck.
Personally I ignore the erratic readings. I go for the solid readings. Sometimes I'll dig up a bouncer, if its consistent.
I started detecting about this time of year back in '03. and so far I found only 4 gold rings. a bracelet and the necklace I found yesterday. And that's only been during the past 2 years....So you been in this hobby about a year now, right? You got a great detector. And sooner or later you're gonna find a big fat gold ring. And thousands and thousands of pull tabs.