A glory is the technical name for a full circle rainbow, such as is sometimes (but rarely) seen from below above a waterfall, or below from above a cloud. I am asking this question here. because it concerns an optical device I once owned, and an optical phenomenon I could never understand. I am hoping that a description or explanation of the phenomenon will include terms that will help me in my search for a similar replacement.
The object was a roughly spherical ball of facetted clear cut crystal, with facets symmetrical or roughly so, about 3 inches in diameter, with a flat, opaque, felt-coveted base a little bigger than a quarter. Despite a great deal of trying I never got a good look at that base seen from above, i.e. through the crystal, but I believe it was at least partially reflective.
Seen from an angle anywhere close to from above in ambient light movements of the head and eyes would cause different colors to flow over circles of facets of the same height from the base, so that each circle of facets was one, uniformly changing, color. The color sequences were not a simple rainbow, but I do not remember them well enough to give a more detailed description.
Does anyone understand what facets, (and perhaps what base) could achieve this effect? Does this cut, or more broadly, this optical device or form of prism, or this optical phenomenon, strike a chord in anyone's memory? If so, do any of these things have a name? Even if you have never seen or heard of such a thing, I would love to know how it worked. It always seemed to me as if it should have been impossible.
I think I would have remembered where I bought it, and I don't. I think it was left behind in a house I moved into, or maybe something I picked up off a table in a large rummage sale. In other words, not from the traditional disappearing bottle shop.
The phenomenon of the glory, relevant or no, is discussed here: What is the explanation of the glory (optical phenomenon)?
If what I saw was in fact a glory, reproduced in crystal, then someone somewhere has a good understanding of how glory works.
