Comparison Casio G-Shock GA-2100-4A vs Casio G-Shock GA-100B-4A

A caliber can be described as the type of movement used in a watch. It is expensive and impractical to design a unique movement for each watch model, so most manufacturers often use the same movement in different watch models, sometimes with significantly different designs. The term "caliber" is due to the fact that initially the type of movement was designated by a number (in inch lines) corresponding to its largest size; however, today unique names or alphanumeric indices that are not directly related to sizes are widely used.

Knowing the name of the caliber on which the watch you are interested in is built, you can, if desired, find more detailed information about the mechanism and determine how its characteristics meet your requirements.

The watch has a separate second hand. Note that the location and features of the operation of such an arrow may be different. So, in some watches it is installed on the same axis with the rest of the hands, in others a separate small dial is provided for counting seconds. On some models, the second hand is part of the chronograph (see Features/Features) and only moves when the chronograph is on.

The accuracy of the rate is usually determined by the largest error — the deviation from the reference time, which can occur in a month when the watch is constantly running in normal mode. Accordingly, the smaller the number in this paragraph, the more accurate the clock. In addition, the accuracy of the movement is a kind of status indicator: if the error exceeds the values stated in the characteristics, this may indicate a malfunction in the mechanism.

If the accuracy indicators are the same both in advance and in lag, one number is indicated in the characteristics — for example, 30 sec / month (i.e. +/-30 sec / month); however, many mechanisms have unequal deviations, for example -15/+25 sec/month. Also note that this parameter is relevant only for quartz watches (see “Movement type”): in mechanical models, the accuracy of the rate is noticeably lower, it is measured in seconds not per month, but per day.

Clock face background colour. Indicated for models with pointer or combination dials (see "Dial type"); in purely electronic models, usually, either a grey substrate (for conventional LCDs) or a dark base (for LEDs) is used.

The most popular in modern watches are black, white, silver and blue dials. However, in addition to this, other shades can be found on the market — in particular, beige, yellow, green, golden, brown, red, orange, pink, grey and purple. A special case are watches with chameleon glasses (see below).

Some models are available in several colour options, in such cases these options are listed separated by commas — for example, "white, red, silver." If the dial is painted simultaneously in 2 or 3 colours, they are indicated as a combination — for example, "white with red" or "white with yellow and red". And multi-coloured models include models in which more than 3 colours are used for the dial.

A function found in models with mixed dials (see the relevant paragraph) or additional scales. One of the disadvantages of such models is that in a certain position, the hands can cover the screens or scales, making it difficult to read the information on them. For such cases, the function of moving the hands is provided: at the user's command, the hands move to a position in which they do not cover additional elements of the dial. Also, on command, the arrows can be returned “to their place”; in addition, in some models, the return occurs automatically after a certain time.

How to illuminate the clock face.

— Luminescent coating. A variant used in pointer dials: the hands, and sometimes the scale, are coated with a “phosphorus” coating that glows in the dark. This method of backlighting is inexpensive and can be used even in low-cost models; in addition, it does not require batteries and is suitable even for mechanical watches. On the other hand, coverage is often not as effective as it should be. The fact is that for work it must be “charged” from the sun or another bright light source, and this “charge” is enough for an average of 5-6 hours, and already in the first couple of hours the brightness of the glow drops noticeably.

— Electronic. Illumination based on LEDs or other miniature light sources. Usually, it does not work constantly, but turns on and off by pressing a special button; the exception is LED dials (see "Dial Type"). The main advantage of electronic backlighting is efficiency: it is guaranteed to be enough to view the image on the dial. In addition, such systems do not depend on external illumination, in contrast to the luminescent coatings described above. On the other hand, the lighting requires a battery to operate; therefore, this type of illumination is found exclusively in quartz watches (see “Mechanism type”).

— Luminescent coating / electronic. Systems that combine both types of illumination described above. This optio...n is found mainly among models with combined dials: the hands are coated with a luminous coating, and the electronic backlight is intended mainly for displays and additional scales (and also as a backup option for the hands). The combined backlight is very convenient, however, such watches are somewhat more expensive.

— Tritium illumination. Illumination option found on premium pointer dials. Miniature flasks filled with tritium, a radioactive form of hydrogen, are responsible for the illumination in such models; from the inside, the surface of such flasks is covered with a phosphor, which glows under the influence of tritium radiation. Separately, we note that this radiation does not pose a danger to humans: it does not go beyond the bulb, and even inside its intensity is extremely low. Tritium illumination is expensive, but it is extremely convenient from a practical point of view: "flashlights" work constantly, without batteries and regardless of external lighting, and shine significantly brighter than a conventional luminescent coating. However due to the decay of tritium, they gradually lose their brightness, but this happens very slowly: it takes 12 years to reduce by half, and at least 20 years for the backlight to become useless.

The shape of the watch case; most often the dial has the same shape, but there are exceptions (for example, a rectangular display in a round case).

This parameter practically does not affect the functionality, so the choice in this case is related solely to how convenient and pleasant-looking one or another option is for you. Also, shape data can be useful if the watch is chosen as a fashion accessory that plays a well-defined role in the image being created. As for specific options, round cases are the most common nowadays — they are easy to manufacture, look neat and fit almost any style of watch. Rectangular watches are also quite popular, they can also belong to different styles; however, such cases are more bulky than round cases, and therefore are used less frequently. The square shape is actually a variation of the rectangular shape. Oval is considered to be suitable primarily for women's watches, although there are also single men's models with such cases. There are other types of cases — polygonal, barrel-shaped, as well as products in non-standard design.

— Brass. Inexpensive material used mainly in watches of the corresponding price category. The composition is an alloy based on copper and zinc. Brass bodies have a pleasant golden colour, but their resistance to corrosion is usually very low. Because of this, such watches darken very quickly, and oxides can stain the wearer's skin and even lead to irritation. To correct the situation, various protective coatings, stainless steel covers, etc. can be used; however, even these measures are not able to completely eliminate this drawback.

— Stainless steel. Inexpensive and at the same time very practical material found in watches of all price categories. "Stainless steel" looks good, perfectly resists corrosion and scratches, retains its presentation for a long time and does not cause allergies. However it has a rather large weight, but for many users, the massiveness of the watch is an advantage, not a disadvantage.

— Titan. Premium material used in watches of the corresponding price level. Titanium alloys combine lightness and high strength, in addition, they are less thermally conductive than steel, due to which they do not “cool” the hand. They are practically not subject to corrosion, do not require protective coatings and are hypoallergenic. On the other hand, such cases are quite sensitive to scratches.

— Plastic. Common features of al...l types of plastic are ease of processing, relatively low cost, low weight, hypoallergenicity, moisture resistance and poor thermal conductivity. For a number of reasons, this material is considered optimal primarily for sports watches, including “diving” (waterproof) watches. At the same time, it should be noted that many types of plastic are used in modern watches, including high-strength varieties that are not inferior in reliability to steel. Therefore, this material is found in all price categories, from low-cost to top; The quality of the case is usually directly related to the cost of the watch.

— Aluminium. "Watch metal", considered a little more advanced than stainless steel. The aluminium alloy is also durable, resistant to corrosion and scratches, and has a solid appearance. At the same time, on the one hand, it is noticeably lighter, on the other hand, it is more expensive.

— Copper. By itself, copper has a pleasant reddish-brown tint, but it does not tolerate prolonged contact with the skin — the surface begins to oxidize, which leads not only to skin contamination, but also to irritation. Therefore, this material is usually used in combination with protective coatings. In fact, it has no advantages over the same "stainless steel", and therefore it is used quite rarely — and not so much for practical or even aesthetic reasons, but in order to distinguish watches from other models.

— Carbon. Composite material, in fact, is high-quality plastic: carbon fiber strands filled with polymer filler. Carbon is notable for its combination of low weight with very high strength; in general, it surpasses even steel in reliability; at the same time, it has many advantages of plastic, such as moisture resistance and low thermal conductivity. The disadvantage of such housings, in addition to high cost, is sensitivity to point impacts.

— Ceramics. Ceramics are various materials obtained by sintering and firing at high temperatures. Watch cases are usually made of high-quality ceramics, which are distinguished by their solid appearance and very high scratch resistance, and they cost accordingly. At the same time, they are quite sensitive to shocks, so a ceramic case is often combined with a stainless steel or other metal back cover.

— Gold. The case is made of jeweler's gold or has a gold-plated finish. Note that the colour of such a case can be different: in addition to the classic yellow, there are also white and red gold. Anyway, such watches are very expensive, and look accordingly; they are designed mainly for those who need not so much a device for determining the time as a rich fashion accessory.

— Silver. Although cases made of silver jewelry are much cheaper than gold ones, this material still belongs to the status ones, and is used not so much for practical reasons, but as a symbol of the high cost of watches and the wealth of their owner. However, for a number of reasons, silver has not received much popularity in watches.

— Wolfram. Tungsten alloys are not cheap, but they are very strong and reliable, and also look stylish. Another feature of this material is its very high melting point; from the practical point of view, this point is not significant, but it is important as a fashion detail, emphasizing the high reliability of tungsten. At the same time, for a number of reasons, such alloys are not widely used in watches.

— Bronze. Quite a rare and specific option, used similarly to copper — in order to give the watch a stylish look. The basis of bronze, in fact, is copper, and tin is most often added to this alloy, but other components can also be used. Accordingly, the colour of such material can be different — yellowish, reddish, brown.

The nominal size of a watch case in diameter (for round cases) or width (for other options, see "Case Shape"). In the most miniature modern models, this size is 21 – 25 mm or even less, among the largest there are cases of 46 – 50 mm and even larger.

Larger watches are more convenient in the sense that the dial readings are better visible on them, and it is easier to provide various additional functions in the design. On the other hand, small watches look neater and create less discomfort directly when worn. In addition, female models (see "Gender") are traditionally made more miniature than male ones. So the choice for this indicator depends mainly on the intended specifics of the application: for example, large cases are best suited for outdoor activities and tourism, about 41 – 45 mm in size, for household wear (regardless of gender) — about 31 – 35 mm, and as an accessory to an evening dress, a small watch of 30 mm or less would be more appropriate.

Also note that the size of a compatible strap/bracelet is associated with this indicator — see "Strap Width" for details.