Messina Jewelers Blog


Entries for the ‘Glossary’ Category


We all know that Sapphire Crystal is harder than Glass, however it does have a higher index of refraction which makes it more light reflective. This of course hinders reading the time. For that reason watch manufactures apply anti-reflaction coatings that get rid of the problem. More than one transparent thin layers create a destructive […]

Perpetual Calendar

The Calendar disc of the watch displays the date and in some cases the weekday, month, and year. However, the regular calendar watches do not take into account different lengths of the months making the user need to reset the date 5 times a year when the month does not end on the 31st . […]

GMT Watch

The Earth is divided in 12 time zones also known as meridians. GMT stands for Greenwich Mean Time, which is used as the time zone 0 in the Universal time. In the watch business a GMT Watch implies that the watch displays a second time zone or a 24-hour indication. This is useful for people […]

Watch movement jewels

Sometimes you see that a mechanical watch has 17 Jewels, or 13 Jewels, but what does that mean? They are called Jewel Bearings and are placed at the center of a rotating gear wheel. The jewels are  synthetic Rubies and their purpose is to minimize friction between hardened steel parts, increase accuracy, lower the weight […]


Chronometer term is used to denote a very precise watch. These watches usually have a deviation of less than 5 seconds per day. Only watches that pass the Official Swiss Testing Office for Chronometers (COSC) test standards may use the chronometer word. The test consists of having the watch in observation for a few days […]

Power Reserve Display

All mechanical watches, automatic or manual wind have a power reserve. Power reserve is the charge the watch has before it needs to be wound again. In the case of automatic watches they automatically charge themselves when the wearer is moving. However when the watch does not move or when the watch is manual the […]