Baily's Beads occur just prior to 2nd and just after 3rd contact in a total solar eclipse. This string of pearls is caused by light from the sun's photosphere reaching us through low spots on the edge of the Moon. The diamond ring effect is when only a single bright bead of light is visible. Although described by Francis Baily in 1836, the phenomenon was first reported by Isaac Newton in 1715 [ Wikipedia].

North is to the right. Taken with a Sony a6300 camera with Vivitar 200mm prime lens and 2X teleconverter at 2017-08-11 17:46 UT from Torrington, Wyoming. Exposed f11 for 1/4000 sec at ISO 100. Exposure adjustment and final crop in Photoshop.