AR is the abbreviation for anti-reflective. Some manufacturers coat the inside or outside of the crystal of their watches with a thin film that cuts down on the reflections visible when viewing the dial. This anti-reflective film sometimes gives a slight blue tint to the crystal. The effect of the coating is that the watch crystal appears to be invisible at certain viewing angles. Also the watch is viewable in outdoor setting where without the coating the glare would make reading the dial difficult.

Manufacturers, like Panerai, Zenith, and Breitling, use this coating extensively through their product line.

Replica Watch missing anti-reflective coating is one of the easiest way to spot a replica. Move the watch around and view it from different angles. If the crystal remains glossy and reflective from various angles then it does not have the coating. This is great way to spot fake Panerais and Breitlings as they are great proponents of the coating. But this way is no longer be effective when spotting high-end or Swiss grade replica Breitling and Panerai watches sold in our site.

In the past, due to its expensive price, sapphire glass was only used in high-end brand watches. Especially the arched, spherical and polygonal sapphire, their craftsmanship is more complex. But now, sapphire glass is very common and is widely used in watch-making, its price is also much cheaper than before.

As you know, sapphire glass is very hard, wear-resistant, and for all watches that use sapphire glass, there is a “SAPPHIRE” identity on the caseback.

Sapphire glass can also improve watch’s waterproof performance, especially the diving watches, which can dive to 300 meters, the thickness of their sapphire glasses is up to 3mm-4mm, so as to withstand the enormous pressure in the deep sea.

But now, how to identify sapphire glass ? Following are some methods.

1, Use equipments to detect

Although sapphire crystal glass is artificial, it has the same refractivity as the natural sapphire, both are 1.76-1.77. Because sapphire is crystalline substance, so like the crystals, it has a birefringence, which is 0.008. This can be seen clearly when rotating the polarizer of eyepiece.

The flat crystal glass is easy to detect, but you have to smear some refraction oil on the surface when detecting a domed one. Refractive index of mineral glass is about 1.52 and it has no birefringence, so it is easy to distinguish between it and the sapphire.

2, Dripping method

Drip a drop of water on the glass’s surface, if the water drop is presented as beaded, then the glass is sapphire, if the water drop spreads out, then it is common glass, not sapphire. Although this method is not known by most people, it is very effective.

3, Check the identification and the hardness of the glass

On the caseback of a original watch, there is a “SAPPHIRE” or “Sapphire Crystal” identification and sapphire crystal glass is also widely used in replica watches. Besides, a sapphire crystal won’t scratch when you drag a razor across its surface.

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.

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 crystal made of ?

They can be made of any of three materials:

a, Plexiglass. A clear, lightweight type of plastic.

b, Ordinary glass. Like that used for windows, and usually refered to in the watch business as “mineral glass”.

c, Synthetic sapphire. Some crystals are made of both mineral and sapphire glass.

3, What are the advantages and disadvantages of each material ?

Plexiglass, as you would expect, is the least expensive. It is also the least likely to shatter and the most likely become scratched. Mineral glass, even though it has been hardened by a tempering process, is more likely to break than plexiglass. But is 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 ?

Click the link to view the answer.

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.

6, Are all scratch-resistant crystals made of synthetic sapphire ?

No. Some mineral-glass crystals are also marketed as “scratch resistant.” These crystals have a hard coating that makes them less likely to get scratched.

7, How much do watch crystals cost to replace ?

Consumers can expect to pay anything from perhaps $20 to $25 for a plexiglass crystal to more than $100 for a shaped synthetic sapphire one. (At Baume & Mercier, for example, synthetic sapphire crystals range from $65 to $135.) The average cost of a round mineral crystal is about $30 to $60. An anti-reflective coating adds to the cost of any crystal. In general, the more expensive the watch, the more the consumer will have to pay to replace its crystal.