Chrysoprase is a distinct gemstone quality variety of chalcedony quartz, a cryptocrystalline form of silicon dioxide. Chrysoprase is highly prized for its opalescent minty, apple-green color, which is especially unique and is owed to its distinctive coloring agent.Deeper colors are considered more desirable, but once the color reaches a certain depth, the stone may be classified as 'prase', which is not as desirable as chrysoprase. Chrysoprase color can fade under prolonged exposure to heat or direct light, but in many cases, the color may be restored after absorption of moisture.Chrysoprase is typically translucent to opaque. Translucent specimens are considered most valuable. When cut and polished, it has a vitreous to waxy luster. Most chrysoprase forms very clean with regard to clarity, but an uneven, cloudy distribution of color is quite common.