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Glossary: Useful Terms Relating To Watches & Jewellery
Emeralds
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Very hard, green precious stones. Flaws and cloudiness (called jardin) are very common in emeralds, so many emeralds are oiled, irradiatied, and dyed to improve their look. Synthetic emeralds have fewer imperfections and are very hard to distinguish from natural emeralds. Emeralds belong to the beryl group of stones (which also includes aquamarines, morganite, and chrysoberyl), which have large, perfect, six-sided crystals. Emeralds were long thought to have healing powers, especially for eyesight.
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Emerald cut
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A cut that is used for large transparent gemstones, such as diamonds and emeralds, so that the table and the contour of the stone are square or rectangular and the sides are step cut.
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Enamel
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Vitreous substance, opaque or transparent, that is fired at a high temperature and used to decorate dials, cases, etc. Several successive firings take place in an oven heated up to 840° C. Some techniques date back to ancient China.
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Equation of time
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The difference between mean solar time (our legal time with a consistent 24-hour day) and true solar time at any given time. This difference, which is compensated four times a year, ranges from about +14.5 minutes in February to about –16.5 minutes in November.
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Escapement
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Set of parts (escape wheel, lever, roller) which converts the rotary motion of the train into to-and-fro motion (the balance).
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