Agreed. There's nothing wrong with admiring and in many ways it's a great compliment to the owner. But there's no need for personal comments or judgment.
My husband & I just got back from dinner & since the restaurant was very crowded, we sat at the bar to eat. There was a couple sitting next to us & the woman, who looked to be in her early 50's, was very stylishly dressed & wearing an absolutely stunning diamond dome ring on her right hand. I said, "Pardon me, but I just wanted to say that your ring is stunning!" That was all I said. She just smiled & said "Oh, thank you" but her husband's face just lit up with a huge grin & said he had bought it for her for their 30th wedding anniversary. My husband even said it was beautiful. Her husband was so proud.
I don't think there's anything wrong with complimenting someone on their style, accessories, or jewelry. In fact, I appreciate it when someone compliments me on something I'm wearing. But I do draw the line a questions about cost, where it came from, ect.