Glucydur, GMT, Gong, Guilloché
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Glucydur
Bronze and beryllium alloy used for high-quality balances. This alloy assures high elasticity and hardness values; it is non-magnetic, rust proof and has a very reduced dilatation coefficient, which makes the balance very stable and assures high accuracy of the movement. |
GMT
Abbreviation for Greenwich Mean Time. As a feature of watches, it means that two or more time zones are displayed. In this case, the second time may be read from a hand making a full rotation in a 24-hour ring (thereby also indicating whether it is am. or p.m. in that zone). |
Gong
Harmonic flattened bell in a steel alloy, generally positioned along the circumference of the movement and struck by hammers to indicate time by sounds. Size and thickness determine the re-suiting note and tone. In watches provided with minute-repeaters, there are often two gongs and the hammers strike one note to indicate hours, both notes together to indicate quarters and the other note for the remaining minutes. In more complex models, equipped also with en-passant sonnerie devices, there may be up to four gongs producing different notes and playing even simple melodies (such as the chime of London's Big Ben). |
Guilloché
Decoration of dials, rotors or case parts consisting of patterns, made by hand or engine-turned. By the thin pattern of the resulting engravings—consisting of crossing or interlaced lines—it is possible to realize even complex drawings. Dials and rotors decorated in this way are generally in gold or in solid silver.
Surface decoration, normally on the dial, whereby a grooving tool with a sharp tip is used to cut an even pattern onto a level surface. The exact adjustment of the tool for each new path is controlled by a device similar to a pantograph, and the movement of the tool can be controlled either manually or mechanically.
Real guillochis (the correct term used by a master of guilloche) are very intricate and expensive to produce, which is why most of the dials decorated in this fashion are produced by stamping machines.
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