This was a 90’s children’s mystery novel that I read as a 3rd or 4th grader in 1996 or so. It was an un-illustrated chapter book. I can’t remember much else about the plot other than the characters were sorting out someone’s estate and found a very fine piece of stained glass art (lamp, vase or pitcher perhaps). The author did an excellent job describing the art – that’s what all my friends and I loved about the book. I also remember at the end of the book they are able to see all of the other pieces of the art collection that belonged with it.
Could it have been an A-Z mysteries novel? Or a Boxcar Children novel?
I was going to suggest E. L. Konigsburg’s “The Mysterious Edge of the Heroic World,” but the significant piece of art in that is a painting, not stained glass. Still, I’ll throw it out there just in case.