About Emerald :-Emeralds, like all colored gemstones, are graded using four basic parameters–the four Cs of connoisseurship: color, clarity, cut and carat weight. Normally, in the grading of colored gemstones, color is by far the most important criterion. However, in the grading of emeralds, clarity is considered a close second. A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of transparency to be considered a top gemstone.Emerald is regarded as the traditional birthstone for May as well as the traditional gemstone for the astrological sign of Cancer. One of the quainter anecdotes about emeralds was told by the 16th-century historian Brantôme, who referred to the many impressive emeralds the Spanish under Cortez had brought back to Europe from Latin America.