Diamond Ring Effect

The diamond ring is the last flash of sunlight just before totality and the first just after it. In the final seconds before second contact, the last of the Baily's beads shrinks to a single brilliant point while the faint inner corona is already glowing around the black Moon, so for a moment the scene looks like a diamond set on a glowing ring. The point fades, the sky darkens and totality begins. At third contact the effect returns on the opposite side of the Moon as the first sunlight breaks through, and that second diamond ring is the signal to put eclipse glasses straight back on. Each diamond ring lasts only a few seconds, and photographers prize it, though it needs a much shorter exposure than the corona. Near the edges of the path, where totality is short, the two diamond rings can come almost one after the other. It is seen only at total eclipses: at an annular eclipse the Moon never covers the Sun, so the bright ring of sunlight stays visible throughout and the corona never shows. Together with Baily's beads it is the clearest sign that totality is about to begin, and for many people it is the most memorable moment of the whole eclipse.