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
Hooker Emerald Brooch Emerald at the centre of the brooch. Ten pairs of baguette-cut diamonds project between the spokes from behind the emerald towards the platinum band. The Hooker Emerald itself weighs . It measures to a side and is remarkably free of inclusions for its size. The gem's cut gives the appearance of a series of concentric squares within the gemstone (known as a beveled square emerald cut.) In total, the brooch contains approximately of diamonds. The Hooker Emerald was extracted from an unidentified mine in Colombia in the 16th or 17th century. The rough emerald was sent to Europe by Spanish