Gemstone irradiation produce mixtures of blue and yellow-to-brown colors, so heating is required as an additional procedure to remove the yellowish color. In some cases, the new colors induced by artificial irradiation may fade rapidly when exposed to light or gentle heat, so some laboratories submit them to a "fade test" to determine color stability. Sometimes colorless or pink beryls become deep blue upon irradiation, which are called Maxixe-type beryl. However, the color easily fades when exposed to heat or light, so it has no practical jewelry application. Gemstone irradiation The gemstone irradiation is a process in which a gemstone is artificially
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