Some rings are clearly artefacts manufactured by ordinary, if highly-skilled, craftsmen, wrought from recognisable materials, worked with familiar techniques, and used and well-worn over long reaches of time. Some are now in need of conservation and care, but some are as indestructible as a steel hubcap.
Others would seem to be the work of magicians, conjuring impossible, other-worldly things. In this case, a torus of bright, mobile water in which two miniature trout swim, eternally. That's one cabinet in the museum that won't need hydration, at least. Just a supply of fruit-flies, to encourage the trout to leap periodically into space and fall back into their watery domain, to the delight of younger visitors.
And in this third case, the ring contains a roiling furnace of crystalline, cold fire, full of shape-shifting faces and figures.
In what distant deeps or skiesTo paraphrase Ted Hughes' Crow, "Mine, evidently". [Cue maniacal laugh...]
Burnt the fire of thine eyes?
On what wings dare he aspire?
What the hand dare seize the fire?