Well Marc, we would all love to say that "Gold rings are always going to read 7..." on the Quattro but the fact is that they can (and do) come in anywhere along the scale. Your "7" may be right for a thin-band ladies 14K or 18K diamond ring. But then comes along a nice "Pimp daddy fatty" 10K thick men's ring that can be as high as 30-ish. And then there's everything in between. So SIZE DOES MATTER!

And then there's the gold content. 10K is only 40% gold. 24K is 99.99% pure gold. Big difference in how they read on the Quattro or any detector. See this link: http://www.gottrocks.com/gold_and_precious_metals_information.htm
Also, it should be noted that if you're hunting the beach and you are discriminating out ANYTHING AT ALL, you WILL miss gold rings and jewelry. And when you bring chains into the mix, it takes a pretty special machine, a careful search technique, and sometimes plain dumb luck to find a lot of the chains out there. Because unless it's balled up, the machine will normally only "see" one link or the clasp. And that can mean a signal that will even read in the iron (negative number) range. So if you're not digging it all at the beach you won't get many gold rings. Aluminum and gold are very close in their relative conductivity and there isn't a machine out there that can tell you the difference between a pull tab and a $6000 diamond solitaire. With experience though, and with learning the tones of the machine and common numbers you WILL be able to tell with fair certainty when you have a penny, some tin foil, and a bottle cap. And maybe a pull tab. But unless you're in a trash pit of a beach, be safe and at least dig everything between about 0 and 38. If you have a whole lot of pennies and they're all coming up 34 then pass them up if you like. But forget the "7" thing. Because just about everybody will tell you that nickels are one of the "hot spots" for gold rings and a machine that can get a lot of nickels is on the path to gold. And we know those are 14 or so on the Quattro, which is twice 7. And then there's your own 19. And silver rings will come in between 35 and 38 usually.
One thing I always recommend is taking a blanket to a clean area and then laying out (spread apart) all the jewelry you have, different coins, bottle caps, pull tabs, chains, charms, aluminum trash, foil...everything you expect to encounter. Now sweep them all one at a time and compare. Compare how they SOUND and act. Look at how they read numerically but also note the major difference not only in tone but in "quality" of the sound of a gold ring compared to foil or a scrap of aluminum trash. And note the differences in how they pinpoint. When you learn these things you will be a lot more certain of what's under the coil than with what number it's reading.
My two cents...