Acrylic Crystal:
Sometimes referred to as Hesolite, an acrylic crystal is made up of plastic composite that is generally less expensive and less durable than a sapphire or a mineral crystal. It’s flexible, malleable make up means it will not shatter on impact. It also produces fewer glares under bright lights and can be easily polished.

Alarm:
A device that makes an alerting sound at a preset time. Alarm watches can be either quartz or mechanical.

Altimeter:
A function, commonly found in pilot watches or inside a pressurized airplane cabin, that shows altitude by responding to changes in barometric pressure.

Analog Watch:
A watch that has a dial, hands, numbers, or other types of markers that present a total display of 12 hours.

Analog-Digital Display Watch:
A watch that shows the time by means of hands (analog display) as well as numbers (digital display), usually found in sport watches. The analog display has a traditional dial with hour, minute, and sometimes seconds hands. The digital display shows the time in Arabic numerals with a liquid crystal display.

Annual Calendar Watch:
A watch showing the day, date, month, and 24 hours, adjusting automatically for short and long months. The calendar needs setting only once a year between the end of February and the first of March.

Atmosphere (ATM):
Measures the normal pressure of the air at sea level. It is used in watchmaking to indicate water-resistance.

Atomic Calendar:
Makes allowances for months of different lengths, and leap years. Some are pre-programmed until 2039.

Atomic Clock:
Currently, the most accurate timekeeping devices on earth. These are accurate to 1 second in 1,400,000 years. This information is broadcast throughout the day from a radio transmitter in Ft. Collins, Colorado.

Atomic Time Standard:
Provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division in Boulder, Colorado, atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America, enabling some atomic watches to correct themselves to the exact time.

Atomic Timekeeping:
A feature that causes the watch to update daily, using a radio signal broadcast from Ft. Collins, Colorado. All that needs to be set is the time zone.

Bezel:
Generically, the upper part of the watch body. Specifically, it usually refers to a ring that goes around the outside of the crystal. On jewelry watches, for instance, the bezel may contain a ring of diamonds. On sports watches, the bezel may show calibrated markings and have the ability to rotate in one or two directions.

Case (Watch Case):
Refers to the metal housing that contains the internal parts of a watch. Most cases are made up of stainless steel, but titanium, gold, silver, and platinum are also used.

Chronograph:
A multifunction sport watch with a stopwatch function. Most have two or three sub-dials or mini dials for measuring minutes and hours. When used in conjunction with specialized scales on the watch dial, it can
perform many different functions, such as determining speed or distance (see tachometer and telemeter). Some chronographs can time more than one event simultaneously (see fly back hand and split seconds hand).

Countdown Timer:
A function that lets the wearer monitor how many hours, minutes, or seconds have elapsed from a preset time. Some countdown timers sound a warning signal a few seconds before the time runs out. These are useful in sporting events, such as races.

Crown:
Often referred to as the winding crown or winder, a knob used for winding a manual watch, setting the hands to the correct time, and setting the date in calendar-equipped watches. On diving or sport models, the crown may screw down onto a threaded tube, which protrudes from the watch case to better ensure superior water-resistance.

Crystal:
The covering of the watch dial. Acrylic, mineral, and sapphire are three types of crystals commonly used in watches. Acrylic crystal is an inexpensive plastic that allows shallow scratches to be buffed out. Mineral crystal is composed of several elements that are heat-treated to create an unusual hardness that helps resist scratches. Sapphire is the most expensive and durable crystal, approximately three times harder than mineral crystals and 20 times harder than acrylic crystals.

Depth Alarm:
Divers wear depth alarm watches that sound when the wearer exceeds a preset depth level. In most watches, the alarm stops sounding when the diver ascends above the preset level.

Depth Sensor/Depth Meter:
Divers wear depth sensor or depth meter watches to determine their depth level by measuring water pressure. Readings may be shown using analog hands and a scale on the dial or on a digital display.

Digital:
A type of display that first appeared in the 1970s on wrist watches. Since then, digital watch technology has vastly improved, and continues to add on new and helpful features. In general, functions in digital watches work by push-buttons, either on the side of the watch case, or on the surface of the watch itself. Many kids’ watches feature digital-displays, as well as sports watches.

Fishing/Hunting Time:
Fishermen & Hunters have used the phases of the moon to predict the best time for fishing/hunting. These watches show moon age; time to fish/hunt, and sunrise/sunset based on set Latitude and Longitude.

Flyback Hand:
A flyback hand is an additional hand on a chronograph watch that moves with the seconds hand, but can be stopped independently to measure a preset interval of time. It can then “fly back” to catch up with the seconds hand. This feature is useful for capturing lap times as well as finish times.

GMT Time zone:
Greenwich Mean Time (GMT), also known as Zulu Time, is set to the international clock in Greenwich, England. Through an additional hour hand, it reflects the world time on a 24-hour scale and is used by pilots across the globe.

Karat or K:
A karat is an indication of a metal’s purity, expressed as proportions of 1/24th of the pure metal used in the alloy. Metals such as gold are too soft in their pure state to use in jewelry, so they are typically made into an alloy for strength. 24K (equal to 24/24ths) is pure metal, and 18K is 18 parts pure metal mixed with 6 parts of other metals. That translates to 18/24=0.750, which is 75% pure or 750 parts per thousand.

Movement:
Movement refers to the means by which a watch keeps time and often includes the power source. For example, a watch with mechanical movement uses a spinning balance wheel powered by a tightly wound
spring. A watch with Quartz movement measures the vibrations in a piece of Quartz and often is powered by a battery.

Pedometer:
Responding to the impact of the wearer’s steps, a pedometer counts the number of strides a wearer takes.

Perpetual Calendar:
A perpetual calendar adjusts automatically to account for different lengths of months (30 or 31 days) and leap years. Perpetual calendars, which can be powered by Quartz or mechanical movements, are programmed to be accurate until the year 2100.

Quartz:
A Quartz is a caliber that uses the vibrations of a tiny crystal to maintain timing accuracy. The power comes from a battery that must be replaced about every 2-3 years. In recent years, new Quartz technology enables the watch to recharge itself without battery replacement. This power is generated via movement similar to an
automatic mechanical watch, or powered by light through a solar cell (Kinetic & solar-tech).

Register:
The register is another name for a sub dial that is usually found within the watch’s main dial. An example is a chronograph where there are registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.

Second Time Zone Indicator:
The second time zone indicator is an additional dial that can be set to another time zone. It lets the wearer keep track of local time and the time in another country simultaneously.

Shock Resistance:
As defined by U.S. government regulation, shock resistance is a watch’s ability to withstand an impact equal to that of being dropped onto a wooden floor from a height of three feet.

Solar Powered:
Solar powered refers to a type of Quartz movement where the batteries are recharged via solar panels on the watch dial. They have a power reserve so they can run in the dark.

Split Second:
A split second is a feature on a chronograph that is two hands: one is a fly back and the other is a regular hand. In order to time laps or different finishing times, the wearer can stop the fly back hand independently while the regular hand keeps moving.

Stainless Steel:
Stainless steel is an extremely durable metal alloy (chromium is a main ingredient) that is virtually immune to rust, discoloration, and corrosion. It can be highly polished, thus resembling a precious metal. Stainless steel is often used on the backs of watchcases that are made of other metals. A metal of choice, stainless steel is used to make high quality watchcases and bracelets. It is also hypoallergenic because it doesn’t contain nickel.

Stopwatch:
A stopwatch with a second hand measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a “chronograph.”

Sub dial:
A sub dial is a small dial used for several purposes, such as keeping track of elapsed minutes or hours on a chronograph, or to indicate the date.

Titanium:
Titanium is a “space age” metal, often having a silver-gray appearance. Because it is 30 percent stronger and nearly 50 percent lighter than steel, it has been increasingly used in watch making, especially sport
watch styles. Its resistance to salt water corrosion makes it particularly useful in divers’ watches. Since it can be scratched easily, some manufacturers use a patented, scratch-resistant coating. Titanium is also hypoallergenic.

Water-Resistance:
Water-resistance describes the level of protection a watch has from water damage. A watch bearing the inscription “water-resistant” on its caseback can handle light moisture, such as a rainstorm or sink splashes, but should not be worn swimming or diving. If the watch can be submerged in water, it must state at what depth it maintains water-resistance, i.e. 50 meters (165 feet) or more on most sport watches. Below 200 meters, the watch may be used for skin diving and even scuba diving depending upon the indicated depths.

Waterproof:
Waterproof: An illegal and misused term: No watch is fully 100% waterproof. Waterproof means the ability to completely exclude the possibility of water entering into any working portion of a watch. According to the Federal Trade Commission, no watch is fully 100 percent waterproof and no manufacturer that sells watches in the U.S. may label any of their watches as “waterproof.” The FTC stipulates that watches be referred to as “water resistant.”