Emerald/Esmeralda from Guatemala is omphacite jade. According to the GIA, omphacite, if it is green, is the third type of jade; nephrite and jadeite being the other two. Guatemalan omphacite jade, known as Emerald / Esmeralda, is extremely dark green. It needs to be worked thin or back lit to see the color. The numerous fractures or clouds can be used to good effect.