Emeralds are the green gem variety of the mineral beryl (Be3Al2(SiO3)6) and they are identical to other types of beryl except for their chromium and (sometimes) vanadium content: it is the chromium that gives emeralds their bright green color. The toughness (resistance to breaking) of emeralds is classified as generally poor: the Beryl has a hardness of 7,5 – 8 on 10 poin Mohs scale of mineral hardnes.
Like all colored gemstones the emeralds are graded using four basic parameters – the four Cs of Connoisseurship: Color, Cut, Clarity and Crystal. The word gemstone comes from the habe of the jewelers that, before the 20th century, used the term water as a gem of the finest water to express the combination of 2 qualities: color and crystal. In the grading of colored gemstones color is the most important criterion, crystal is considered the second criterion. They are both necessary condition.
Science Why are emeralds green /Dan-Marius.ro – my slice of internet / Oradea, Bihor, Romania.
