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diamond-ring effect
1. A phenomenon seen as a flash of sunlight shines down a lunar valley during a total solar eclipse.
2. An effect created as the total phase of a solar eclipse is about to begin, when the last Baily's bead, a remaining bit of phosphere, glows so intensely by contrast with the sun's faint corona that it looks like the jewel on a ring.

It also refers to the equivalent phase at the end of totality.

This entry is located in the following unit: Astronomy and related astronomical terms (page 8)