kind of a mystery/surprise men's ring

This ring has "a history" with me, albeit a brief and maybe not too interesting one. It was 'borrowed' to me years ago from a dear friend to wear for an occasion, then never asked for in return. ;-) I assumed at the time it was entirely costume jewelry but it was sufficiently bling-ie for the moment, afterward it just went into the box/drawer with the rest of my jewelry I don't wear too much. ;-) :-)

FFWD to recently when I came across it again and remembered that it still fit my finger. On a similar whim I took a little bit of silver polish to it with a toothbrush and was quite surprised at what came out -- it had always been a rather dull (unpolished) metallic color, but I had *no idea* it was so shiny under there...in fact I kinda thought it was supposed to be (mostly worn off) 'gold plate'...but WOW...! Only then did I look at with my magnifying glass, where I found a 925 stamp inside along with something else I can't recognize opposite that. (pic 3)

Here's the mystery part: I then took it to a jeweler to ask "is this anything?". His opinion was that the stones (six set in a ring around a slightly larger 7th) are CZ (no surprise there, to me) but he did *not* think the band was actual sterling despite the mark. Finding that to be a most curious evaluation, I took it to a second jeweler for the same question. (without sharing the previous opinion) He concurred that the stones are CZ but didn't have the slightest doubt that the band was real -- he even took a few moments to professionally clean and polish it for me resulting in what I'm showing here, now. Despite it being difficult to photograph please trust me when I say the thing fairly well GLEAMS like CRAZY -- like I would have never imagined it could -- and I've got more compliments while wearing it a few times since than most any other bit of jewelry I've worn in a LONG time???!!! <WOW, again!!>

I'm not gonna mark this as a mystery but I *will* ask the collective CW knowledge base of friends and experts -- WHAT SAY YE?? Has anybody come across jewelry "mis-stamped" with a sterling mark?? Does anybody recognize anything about it that would suggest it could be a counterfeit/knockoff of something else?? IS there any actual mystery about it, or do I just need to wonder a little bit more about 'jeweler #1' and his skills or why he'd suggest that about it...??? (or for that matter, is there a chance that any of the stones *are* real...??)