Gemstone few as one in a million atoms. These so-called impurities are sufficient to absorb certain colors and leave the other colors unaffected. For example, beryl, which is colorless in its pure mineral form, becomes emerald with chromium impurities. If manganese is added instead of chromium, beryl becomes pink morganite. With iron, it becomes aquamarine. Some gemstone treatments make use of the fact that these impurities can be "manipulated", thus changing the color of the gem. Gemstones are often treated to enhance the color or clarity of the stone. Depending on the type and extent of treatment, they can affect the
Shades of green of its unofficial mascot, the Dartmouth Indian, in 1974. Dartmouth green and white are the main colors of Lithuanian basketball club Žalgiris Kaunas. "Emerald", also called "emerald green", is a tone of green that is particularly light and bright, with a faint bluish cast. The name derives from the typical appearance of the gemstone emerald. The first recorded use of "emerald" as a color name in English was in 1598. Ireland is sometimes referred to as the "Emerald Isle" due to its lush greenery. The May birthstone is emerald. Seattle is sometimes referred to as the "Emerald City", because its