Our new models and solvements for all problems you may encountered at and after buying watches from us.

1. What is a watch crystal?
A watch crystal is a transparent cover that protects the watch face. Note that, coincidently, the word “crystal” is also used to denote the tiny piece of quartz that serves as an oscillator in a quartz watch. These two types of crystals have nothing to do with each other. The latter is usually called a “quartz crystal” to prevent confusion.

2. What are watch crystals made of?
They can be made of any of three materials: 1- plexiglass (a clear, lightweight type of plastic), 2- ordinary glass – like that used for windows, and usually referred to in the watch business as “mineral glass” or 3- synthetic sapphire (see question 4). Some crystals are made of both mineral and sapphire glass. Seiko, for example, makes some watches with crystals made of mineral glass covered with a layer of synthetic sapphire. Seiko calls this composite material “Sapphlex”.

3. What are the advantages and disadvantages of each materials?
Plexiglass, as you would expect, is the least expensive. It is also the least likely to shatter and the most likely to become scratched. Mineral glass, even though it has been hardened by a tempering process, is more likely to break than plexiglass. But it is also more scratch-resistant than that material. Synthetic sapphire is the most expensive glass crystal material and the most scratch resistant. Because it is so hard, it is also brittle, and shatters more easily than mineral glass or plexiglass.

4. What exactly is synthetic sapphire?
It is a very hard, transparent material made of crystallizing aluminum oxide at very high temperatures. Chemically, synthetic sapphire is the same as the natural sapphire used in jewelry, but without the coloring agents that give the gemstone its various hues.

When it is heated, the synthetic sapphire forms round masses that are sliced into pieces with diamond-coated saws. These disks are then ground and polished into watch crystals. (One reason sapphire crystals are relatively expensive is that the tools required to make them are costly.)

Sapphire (whether natural or synthetic) is one of the hardest substances on earth. It measures 9 on the Mohs scale, which is a system for rating the relative hardness of various materials. (Diamond measures 10, the highest rating.) Watch crystals made of synthetic sapphire are often marketed as “scratch resistant”, meaning they are very difficult – but not impossible – to scratch. Diamond can scratch them; so can man-made materials that incorporate silicon carbide, with, with a Mohs rating of between 9 and 10, is, like diamond, harder than sapphire. These materials are sometimes used to make simulated-stone surfaces for furniture or walls. The watch wearer should note that accidentally scraping a sapphire crystal against such a surface could cause a scratch.

5. Can you tell if a crystal is made of sapphire by looking at it?
No. Mineral glass and sapphire generally look the same. A surefire way to tell them apart (albeit an often impractical one) is with a scratch test, says Johann Jorgo, technical director at Baume & Mercier Inc. New York. A stainless steel knife or screwdriver will scratch a mineral-glass crystal but not a sapphire one.

BEZEL The ring surrounding a watch’s dial. Rotating versions have markings to indicate different time zones, elapsed time or other functions.

CALIBRE Now used as a term to identify the basic movement, for example, “TAG Heuer’s Calibre 11.”

CHRONOGRAPH A wristwatch that also includes stop-watch functions to mark intervals of time.

CHRONOMETER A watch that has been fully tested at Contrôle Officiel Suisse des Chronomètres to ensure its timekeeping accuracy according to temperature, position and other variables.

COMPLICATION Any function found on a watch beyond telling the hours, minutes and seconds—for example: date, moon phase or chronograph.

DIVING WATCH A watch specially designed to survive long periods immersed in water and at depth, while also indicating elapsed time to tell divers how much of their air supply remains.

FLYBACK Type of chronograph that instantly restarts timing when the hand is reset to zero.

GMT Short for Greenwich Mean Time, a watch able to show time in two or more time zones.

MANUAL WINDING The watch has to be wound by hand, via the crown (usually positioned next to the 3), typically once a day.

MANUFACTURE Always pronounced with comedic French accent; means a watch company that makes its own movements.

MINUTE REPEATER A watch that can indicate the time through chimes. Originally developed so one could tell the time in the dark.

MOON PHASE Device that shows the phases of the moon—only of any practical use to sailors and werewolves.

NOVELTY In watch parlance it means a brand-new model. However, it is often ironically meant to mean mere novelties in the derogatory sense.

PERPETUAL CALENDAR Function that shows the day of the week, date, month as well as leap years.

PILOT’S WATCH Usually oversized and designed for maximum legibility. Can also feature chronograph and GMT functions.

POWER RESERVE Device that shows how much time a watch will run before it needs to be wound again.

TOURBILLON A rotating cage containing the balance devised by Breguet to counter the effects of gravity on pocket watches. Difficult to manufacture, beautiful to behold, functionally useless in wristwatches.

TRIPLE CALENDAR A watch able to show day, date and month.

WORLD TIMER Like a GMT (see above), but able to show all 24 times zones, with names of cities featured as references.

This complication is one of two that are the most popular exports from Switzerland (the other being the chronograph), according to the Federation of the Swiss Watch Industry. This contrasts strongly with the world time watch, which is rarity. Of course, the contrasts don’t end there. Aesthetically, the world time watch and a watch with a second time zone, which we shall call the GMT watch, are totally at odds.

GMT watches are very clean and legible, unless of course there is another complication thrown into the mix. This clean and professional look – very nearly like an industrial tool – is part of the appeal of the GMT watch. Typically, the GMT watch has a central hour and minutes display for the local time, while home time or the second time zone is indicated via a second hour hand, which also operates out of the central hour axis but only makes a circuit of the dial once every 24 hours.

All things being equal, there will be only one crown on a GMT watch. A rotating bezel is useful but not de rigueur. The addition of more than two time zones sometimes means that additional crowns will come into play.

History tells us that the GMT watch came into play at the dawn of the commercial jet age, classics here being from Rolex of course. The original GMT Master watch in 1954 was in fact the first GMT watch ever produced. Though this and other classic GMT watches use just one movement, some watches with more than just a second time zone actually feature different movements.