An easy way to find out: take a stainless steel spoon and airtest that That would account for the composition. To mimic the size, you can take tin-snips, cut a thumb sized piece off the end of a stainless steel spoon (afterall, they're practically disposable, eh?), to test a small piece of stainless steel.
It might try to squeek in high, but they'll have a lousy "edge" to them.
Why would you think that anyone would make a "ring" out of stainless steel? I've never heard of that before (I'm assuming you mean a ring, as in jewelry to wear?). Titanium is a fairly new fad, and it looks like stainless steel. Perhaps you have a titanium ring? They read low, like gold.
Excal 1000, Excal II, Sovereign GT, CZ-20, Tiger Shark, Tejon, GTI 1500, Surfmaster Pulse, CZ6a, DFX, AT PRO, Fisher 1235, Surf PI Pro, 1280-X, many more because I enjoy learning them. New Garrett Ca
Listen to Tom.......You can find a Stainless Steel ring and test it along side the nickel to see what the readings are. Not all detector would read alike.