When choosing a watch, one of the most important yet often overlooked components is the watch crystal—the transparent cover that protects the dial. Whether you’re new to collecting or a seasoned enthusiast, understanding the differences between watch crystals can help you make an informed decision about your next timepiece. In this guide, we’ll break down the three most common types of watch crystals—acrylic, mineral, and sapphire—so you can determine which one is best for you.
A Brief History of Watch Crystals
In the early days of horology, watches didn’t even have crystals. Early pocket watches had closed cases, requiring users to open them to see the dial. Eventually, glass was introduced, but only in high-end timepieces. Fast-forward to today, and crystals have evolved into key components, providing both protection and aesthetic appeal.
Interestingly, one of the early advances in watchmaking came from British horologist Thomas Earnshaw, who managed to reduce the cost of Marine Chronometers by subcontracting their production, making precise timekeeping devices more accessible. Watchmaking history is full of such fascinating stories, and the evolution of the watch crystal is just one chapter in the broader tale of horological innovation.
The Types of Watch Crystals
Today, most watches are fitted with one of three types of crystals: acrylic, mineral, or sapphire. Each type has its own unique properties and benefits, so let’s explore them in detail.
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Acrylic (Hesalite) Crystals
Acrylic, also known as Hesalite, is a type of transparent plastic that has been used in watchmaking for decades. It is lightweight and highly flexible, making it less likely to shatter upon impact. While acrylic is softer than other crystal types and more prone to scratches, it does have the unique advantage of being polishable. Minor scratches can often be buffed out, restoring the crystal to a like-new condition.
Despite its softer nature, acrylic has earned its place in horological history. For example, the Omega Speedmaster, which famously accompanied astronauts to the moon, uses an acrylic crystal. Its non-reflective properties make it ideal for certain applications, especially when a watch is subjected to extreme environments like space or high-altitude expeditions.
Acrylic is also a nostalgic choice, evoking the charm of vintage watches. If you own a timepiece with an acrylic crystal, consider having it professionally polished during restoration to maintain its vintage appeal without distorting its shape.
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Mineral Crystals
Mineral crystal is another popular option, especially in mid-range watches. Made from tempered silica, mineral crystals are more scratch-resistant than acrylic and are commonly found in many modern timepieces. While mineral crystals can scratch more easily than sapphire, they are much tougher and more resistant to breaking than acrylic.
Some brands, like Citizen, offer mineral crystals with an additional sapphire coating for enhanced scratch resistance. This combination provides a durable, cost-effective solution for those looking for extra protection without the price tag of full sapphire.
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Sapphire Crystals
Sapphire is the gold standard for modern watch crystals. Made from crystallised aluminium oxide, sapphire is incredibly hard, ranking 9 on the Mohs hardness scale, just below diamond. This means sapphire crystals are highly scratch-resistant, making them an excellent choice for those seeking long-lasting clarity.
However, this level of durability comes at a price. Sapphire crystals are more expensive to produce, as they require specialised tools to grind and shape the material. Double-domed sapphire crystals, in particular, are costly but offer superior optical clarity by minimising visual distortion.
Many high-end watches, including our own Helicon Master, use sapphire crystals. For our Master model, we opted for a double-domed sapphire crystal with anti-reflective coating on the inside, striking the perfect balance between modern performance and vintage aesthetics. This reduces glare while keeping the outer surface smudge-free, making the watch easy to read in various lighting conditions.
Anti-Reflective Coatings
Both sapphire and mineral crystals can benefit from anti-reflective coatings, which reduce glare and enhance readability. These coatings can be applied to the inside, outside, or both sides of the crystal. While external coatings improve clarity, they can be more prone to smudges and wear. That’s why, on the Helicon Master, we’ve chosen an internal-only coating to ensure long-lasting performance.
Which Crystal Is Best for You?
Ultimately, the choice between acrylic, mineral, and sapphire depends on your lifestyle and preferences:
- Acrylic is perfect for those who appreciate the charm of vintage watches and want a crystal that can be polished and restored easily.
- Mineral is a durable, budget-friendly option that offers decent scratch resistance without breaking the bank.
- Sapphire is ideal for those who prioritise maximum scratch resistance and optical clarity, even at a higher price point.
Conclusion
No matter which type of crystal you choose, rest assured that each has its place in watchmaking. At Helicon Watches, we’ve carefully selected a double-domed sapphire crystal for our Master model, blending modern durability with classic charm.
We hope this guide has shed some light on the different types of watch crystals and their benefits. If you have any questions or want to learn more about our watches, feel free to reach out. Whether you’re a seasoned collector or just starting your horological journey, we’re here to help you find the perfect watch
Looking for your next timepiece? Explore our Helicon Master collection and discover the craftsmanship that sets us apart.
