Rectangle cut peridot post earrings measure 6mm x 3mm, set in .925 sterling silver. ABOUT PERIDOT - August's birthstone, and lovely in any setting, peridot is known as the emotional healing or forgiveness stone. Peridot is also known as the "evening emerald" and is a stone with an oily luster with a transparent yellow-green color. It has the feature of double refraction. When you look through the stone, things appear double, so the facets at the bottom appear to be double the actual number. Whenever you're feeling uncertain or bad about yourself, whatever the reason, wear peridot. Then watch how its shimmering light helps break up those dark clouds around you.