Zurich is the largest city in Switzerland and the capital of the canton of Zürich. The city is Switzerland's main commercial and cultural centre and sometimes called the Cultural Capital of Switzerland, the political capital of Switzerland being Berne. Zurich can be counted as one of the world's preeminent global cities. According to several surveys from 2006 to 2008, Zürich was named the city with the best quality of life in the world. The blue and white coat of arms of Zürich is attested from 1389, and was derived from banners with blue and white stripes in use since 1315 . The first certain testimony of banners with the same design is from 1434. The coat of arms is flanked by two lions. The red Schwenkel on top of the banner had varying interpretations: For the people of Zürich, it was a mark of honour, granted by Rudolph I. Zürich's neighbors mocked it as a sign of shame, commemorating the loss of the banner at Winterthur in 1292.

Emeralds

Emeralds, like all colored gemstones, are graded using four basic parameters – the four Cs of Gemstones: Color, Cut, Clarity and Crystal. The last C, crystal is a synonym that begins with C for transparency or what gemologists call diaphaneity. Before the 20th century, jewelers used the term water as in a gem of the finest water to express the combination of two qualities, color and crystal. Normally, in the grading of colored gemstones, color is by far the most important criterion. However, in the grading of emerald, crystal considered a close second. Both are necessary conditions. A fine emerald must possess not only a pure verdant green hue as described below, but also a high degree of transparency considered a top gem. In the 1960s, the American jewelry industry changed the definition of emerald to include the green vanadium-bearing beryl as emerald. As a result, vanadium emeralds purchased as emeralds in the United States recognized as such in the UK and Europe. In America, the distinction between traditional emeralds and the new vanadium kind reflected in the use of terms such as Colombian Emerald. Scientifically speaking, color divided into three components: hue, saturation and tone. Yellow and blue, the hues found adjacent to green on the spectral color wheel, are the normal secondary hues found in emerald. Emeralds occur in hues ranging from yellow-green to blue-green. The primary hue must be green. Only gems that are medium to dark in tone considered emerald. Light-toned gems known by the species name, green beryl. In addition, the hue must be bright (vivid). Gray is the normal saturation modifier or mask found in emerald. A grayish green hue is a dull green. Emerald tends to have numerous inclusions and surface breaking fissures. Emerald graded by eye. Thus, if an emerald has no visible inclusions to the eye it considered flawless. Stones that lack surface breaking fissures are extremely rare and therefore almost all emeralds are treated, oiled, to enhance the apparent clarity. Eye-clean stones of a vivid primary green hue with no more than 15% of any secondary hue or combination of a medium-dark tone command the highest prices.6 This relative crystal non-uniformity makes emeralds more likely than other gemstones to be cut into cabochons, rather than faceted shapes.