There are a number of factors that will determine the purchase choice when buying a smartwatch. To help the user make an informed choice, we present a guide of the factors that decide the quality of wristwatches, which are related to casing, crystals, electronics, and design.
The first thing that draws attention when choosing a watch is its design and the main material from which it's made. The highest quality materials have always been gold and silver, although in the last two decades sapphire crystal has become increasingly fashionable. Its main strengths are its scratch resistance and durability.
Accordingly, sapphire crystal is the most resistant kind to being scratched. In fact, its hardness is such that it's almost like a diamond. On the Mohs scale, which measures hardness, sapphire crystal is one of the hardest crystals: 9 on the scale, the maximum being 10, which is diamond. As mentioned in the previous paragraph, its main strength is that it does not scratch, i.e., in theory, it could only be scratched by a diamond, which has a higher hardness.
It's important to note that sapphire crystals reflect light, which can be quite annoying. For this reason, it's recommended when purchasing a sapphire crystal watch that it has an anti-reflective coating.
Anti-reflective (AR) coatings are thick nanometer layers of metal oxide materials such as titanium or zirconium oxides. These can be applied on both sides of the glass substrate, or only on the glass inner side. But what is their usefulness? The main one is to help reduce glare and light reflection, i.e., as with soundproof rooms, that cancel noise, anti-reflective coatings cancel incoming light. Depending on the coating thickness, it can reduce from 1% to 98% of light reflection.
In addition to reducing glare, the AR coating can also provide a colorless AR coating, improve scratch resistance, repel water, reduce fingerprints, and provide UV protection. In any case, a standard AR coating may be sufficient as anti-reflective and scratch resistant.
In conclusion, adding an anti-reflective coating to its sapphire crystal will improve its functionality and benefits. Also, if a new watch with these features is not in your best interest, some watch stores offer the possibility to replace the watch crystal with a part that contains AR coatings on both sides of the crystal substrate, or on the inner side only.
Stainless steel, consisting of a basic mixture of carbon, iron, and chromium, has become an ideal watch material. This is due to its high resistance to oxidation, its invulnerability to corrosion by moisture, and its material that prevents irritation to the wearer's skin.
There are mainly three types of stainless steel which vary according to their purity degree. Most high-quality watches use 316L stainless steel, commonly called surgical steel, to offer premium quality at an affordable price. This kind of steel, in addition to the basic mixture of the above metals, is manufactured with added nickel, which is susceptible to corrosion as well as a base metal protector and decorative element.
316L stainless steel, thanks to its low carbon composition and high resistance to chlorides, is used in various fields such as medical for surgical instruments, the petrochemical industry, or nuclear reprocessing. Therefore, we understand that 316L is a material used in various fields other than high-end watches, due to its optimal price and qualities such as resistance to magnetism.
Before giving our recommendation, it seems important to define this section briefly, since it's not usual to recognize this component. We are referring to the BLE (Bluetooth Low Energy) microcontroller, a programmable integrated circuit, capable of executing the commands recorded in its memory, and which fulfills a specific ordered task. About its market, we can say that it's still at an early stage, although Nordic Semiconductor has become one of the leading manufacturers in this field. Thus, our recommendation is the nRF52840 SoC, the most advanced of the nRF52 series.
The BLE Nordic Semiconductor (nRF52840) offers, on one hand, a high memory capacity for both Flash and RAM, a must for demanding AI applications and products. On the other hand, it supports Bluetooth LE, Bluetooth mesh, Thread, Zigbee, 802.15.4, ANT, and proprietary 2.4 GHz stacks. As a result, it offers a wide range of cryptographic options that run highly efficiently independently of the CPU, as well as a high speed for data transfer and power supply to recharge the battery.
To summarize, it achieves exceptionally low power consumption using a sophisticated on-chip adaptive power management system, so if one wants their smartwatch to possess a very high-performance microcontroller with low power consumption, the Nordic Semiconductor BLE (nRF52840) is the best choice.
A very important quality of a watch is water resistance, as many users are interested in wearing it during their water entertainment moments without having to worry about it. Thus, 100 meters (10 bar) water resistance will be suitable for water sports such as recreational surfing or sailing, as well as snorkeling and swimming, but not for professional diving.
Alongside water resistance, smartwatches come with a variety of valuable features that often drain their battery. Even so, the user is often looking for a smartwatch whose battery life lasts as long as possible. Usually, conventional smartwatch batteries can serve for one to two days at a time if fully charged.
The selection and combination of high-quality components is fundamental to Chroneering®,along with the low-energy Scandinavian analog design, and information filtering are the factors that for the long battery life that up to two years. When the battery runs out, the user will not have to buy an out-of-the-ordinary battery, as a normal watch battery will do.