Sapphire vs Mineral Crystal
The crystal is the clear glass over a watch dial, and the choice comes down to two materials with a third for reference. Sapphire crystal -- lab-grown synthetic corundum at around 9 on the Mohs scale -- virtually never scratches, so it is the one to have on a watch you mean to keep. Mineral crystal -- hardened glass at about 5 on the Mohs scale -- scratches more readily but costs less and forgives a knock a little better, which suits a fashion or beater watch. Acrylic rounds out the picture as the soft, cheap, shatterproof plastic of vintage and budget pieces. This guide sets the three side by side -- hardness, scratch resistance, shatter behaviour, cost and whether you can polish them -- and tells you which we stock: Tissot and the better Citizen models use sapphire as standard; fashion-quartz brands such as BOSS, Tommy Hilfiger, Olivia Burton and Vivienne Westwood typically use mineral.
Sapphire vs Mineral vs Acrylic at a glance
| Sapphire | Mineral | Acrylic | |
|---|---|---|---|
| Hardness (Mohs) | ~9 | ~5 | ~3 |
| Scratch resistance | Excellent -- only diamond scratches it | Good -- resists everyday marks | Low -- scratches easily |
| Shatter resistance | Lower -- brittle, can crack on a sharp blow | Good -- flexes and absorbs shock | Highest -- cracks rather than shatters |
| Relative cost | Highest | Mid | Lowest |
| Polishable at home | No -- replaced if damaged | Rarely -- light professional polish only | Yes -- buffs clear with paste |
| Best for | A keeper you wear daily | Fashion or beater watch | Vintage and budget watches |
The two crystals, head to head
The short answer
Sapphire is the one to have if you are keeping the watch -- it virtually never scratches. Mineral is perfectly fine on a fashion or beater watch where price and a little shatter tolerance matter more.
The verdict in one line
For a watch you intend to keep and wear for years, sapphire crystal is worth paying for -- it stays clear and scratch-free for the life of the watch. For a fashion piece, a second watch or a knockabout, mineral crystal is a sensible, cheaper choice that takes the odd scratch but resists shattering a touch better.
When sapphire is right
Choose sapphire when the watch is a keeper -- a Tissot or Citizen you will wear daily for a decade. The face stays as clear as the day you bought it, which protects both the look and the resale value. This is why every Tissot and the better Citizen models come with sapphire as standard.
When mineral is fine
Choose mineral when you are buying on style or budget -- a fashion-quartz watch you will rotate with others, or a watch that will take knocks. It scratches more readily over years of hard wear, but those marks are cosmetic, the watch costs less, and the glass is a touch more forgiving of a sharp blow.
What is sapphire crystal
Lab-grown synthetic corundum -- the same hard material as the gemstone -- sitting at around 9 on the Mohs scale, so in normal wear only diamond can scratch it.
What it is
Sapphire crystal is synthetic corundum: aluminium oxide grown in a lab into a single crystal, then sliced and polished into a clear disc for the watch face. It is the same material as a natural sapphire gemstone, just grown for clarity rather than colour. The metallurgy and detail live on our sapphire crystal guide.
Why it barely scratches
On the Mohs hardness scale sapphire sits at about 9, second only to diamond at 10. In everyday life nothing you meet -- keys, coins, sand, a concrete worktop, a car door -- is hard enough to mark it. That means a dial that stays perfectly clear for the life of the watch, with no swirl of fine scratches building up over the years.
What you pay for
Sapphire is harder to make and harder to machine than glass, so it is the most expensive crystal. On a quality watch that cost is well spent: it is the single feature that keeps the watch looking new. Tissot and the better Citizen models fit it as standard -- see Tissot watches and Citizen watches.
What is mineral crystal
Hardened glass at roughly 5 on the Mohs scale -- cheaper than sapphire, more scratch-prone, but it flexes a little and tends to crack rather than shatter outright.
What it is
Mineral crystal is ordinary glass that has been heat- or chemically-treated to toughen it. It sits at around 5 on the Mohs scale -- well above plastic, well below sapphire. It is the everyday workhorse crystal, found on most fashion and value watches.
How it behaves
Day to day it resists the light marks that a soft acrylic would pick up, but over years of hard wear it will gather fine scratches that sapphire never would. Its upside is forgiveness: glass flexes and absorbs a knock slightly better than rigid sapphire, so on a sharp impact it is a little more likely to survive, or to crack rather than splinter into pieces.
Where you find it
Mineral crystal is the standard glass on fashion-quartz watches -- the BOSS, Tommy Hilfiger, Olivia Burton and Vivienne Westwood pieces in our cabinets typically use it. That is part of how those watches hit their price, and it is perfectly appropriate for a style-led watch.
What is acrylic / hesalite
Clear plastic crystal -- the softest and cheapest, scratches easily but is almost unbreakable and polishes clear at home. Mostly a vintage and budget material.
What it is
Acrylic -- also sold as hesalite or plexiglass -- is a clear plastic crystal, the softest of the three at around 3 on the Mohs scale. It was the standard watch glass for decades before mineral and sapphire took over, and it still turns up on vintage pieces and entry-level watches.
The plastic trade-off
Being soft, acrylic scratches the most easily of any crystal. Its saving grace is twofold: it is almost impossible to shatter -- it cracks rather than splintering, which is why it was chosen for early space watches -- and surface scratches buff straight out at home with a dab of polishing paste. A scuffed acrylic crystal can be made clear again in minutes.
For reference
We carry sapphire- and mineral-glass watches rather than acrylic. Acrylic is included here for context: it is best known on heritage and budget pieces -- the classic example being early moon-watch hesalite crystals -- none of which are part of our current range.
Scratch resistance vs shatter resistance
The real trade-off: hardness buys scratch resistance but costs shatter resistance. Sapphire wins on scratches; softer glass survives a sharp knock a little better.
The trade-off explained
Hardness and toughness pull in opposite directions. Sapphire is extremely hard, so it shrugs off scratches -- but that same rigidity makes it brittle, so a sharp, direct blow can crack or shatter it where a softer crystal would only mark or flex. Mineral glass and acrylic are softer, so they scratch more readily, but they absorb a knock better and are less likely to fail catastrophically.
Which risk matters to you
In real life, scratches are the common enemy -- they come from everyday contact and build up slowly, dulling the dial. A shatter needs a genuine hard impact, which most watches never see. For that reason sapphire's scratch resistance usually matters more than its brittleness, unless the watch leads a rough, high-impact life.
A note on anti-reflective coating
Many sapphire crystals add an anti-reflective (AR) coating to cut glare and make the dial easier to read. The coating itself is a thin surface layer that can scuff over time, even though the sapphire beneath does not -- the best watches put the AR coating on the underside of the crystal to protect it.
Choosing and buying
Which should you choose
Sapphire on a keeper, mineral on a fashion or beater watch. Match the crystal to how long you will keep the watch and how hard a life it will lead.
Match the crystal to the watch
The decision is really about the watch's role. A watch you will own and wear for years deserves sapphire, so it still looks new a decade on. A style-led or second watch you will rotate, or one that will take knocks, is fine on mineral -- you save money and accept a few cosmetic marks over time.
A simple rule of thumb
If you would be annoyed to find a scratch on the glass, buy sapphire. If a scratch would not trouble you -- or you would rather have shatter tolerance and a lower price -- mineral does the job. Acrylic only really makes sense on a vintage watch or where you actively want a crystal you can polish at home.
Crystals at OD's
Tissot and the better Citizen watches use sapphire as standard; fashion-quartz brands -- BOSS, Tommy Hilfiger, Olivia Burton, Vivienne Westwood -- typically use mineral. Buy by brand and you usually buy by crystal.
Sapphire-grade brands
If sapphire matters to you, our Swiss and Japanese watchmakers are the place to look. Tissot fits sapphire crystal across its range, and the better Citizen Eco-Drive models do too -- both built to be kept and worn daily. Browse Tissot watches and Citizen watches.
Fashion-quartz and mineral
Our fashion-watch brands -- BOSS, Tommy Hilfiger, Olivia Burton and Vivienne Westwood -- typically use mineral crystal, which suits a style-led watch at a friendly price. They are made to look great and rotate through a collection rather than to survive a building site, and mineral glass is exactly right for that.
Already own one
If your current watch has a scratched crystal, what you can do about it depends on the glass -- acrylic buffs out at home, mineral can sometimes be lightly polished, and sapphire is replaced rather than buffed. Our guide on how to remove scratches from a watch walks through each case. For the wider material picture, see the watch materials hub.
Frequently asked questions
Is sapphire or mineral crystal better?
It depends on the watch. Sapphire is far harder -- about 9 on the Mohs scale against mineral's 5 -- so it virtually never scratches, which makes it the better choice for a watch you will keep and wear for years. Mineral scratches more easily but flexes to absorb a knock a little better and costs less, which suits a fashion or second watch.
What is sapphire crystal made of?
Sapphire crystal is synthetic corundum -- aluminium oxide grown in a lab into a single clear crystal, the same hard material as a sapphire gemstone. It is sliced and polished into a disc for the watch face. See our sapphire crystal guide for the full detail.
Can sapphire crystal scratch?
In normal daily life, no. At around 9 on the Mohs scale, only diamond and other corundum can scratch sapphire, so keys, coins, sand and concrete leave it untouched. It can, however, crack or shatter under a sharp, direct blow, because being very hard also makes it brittle.
Can sapphire crystal shatter?
Yes, under a hard enough direct impact. Sapphire's hardness comes with brittleness, so a sharp knock can crack it where a softer mineral glass might flex and survive. In everyday wear this is rare -- most watches never take a blow severe enough -- so for most owners the scratch resistance outweighs the shatter risk.
What is mineral crystal?
Mineral crystal is ordinary glass that has been heat- or chemically-hardened. It sits at about 5 on the Mohs scale -- harder than plastic, softer than sapphire. It is the standard glass on most fashion and value watches: more scratch-resistant than acrylic, cheaper than sapphire, and a touch more shatter-tolerant.
Is mineral glass good on a watch?
Yes, for the right watch. Mineral glass is a sensible, good-value crystal on a fashion or everyday watch -- it resists the light marks plastic would pick up and forgives a knock better than sapphire. Its only real downside is that it gathers fine scratches over years of hard wear, which sapphire would not.
What is acrylic or hesalite crystal?
Acrylic -- also called hesalite or plexiglass -- is a clear plastic crystal, the softest type at around 3 on the Mohs scale. It scratches easily but is almost impossible to shatter, and scratches buff out at home with polishing paste. It was the standard for decades and is now mostly seen on vintage and budget watches.
Which crystal is the most shatterproof?
Acrylic is the most shatterproof -- being plastic it cracks rather than splintering, which is why it was used on early space watches. Mineral glass is next, as it flexes to absorb a knock. Sapphire is the hardest but the most brittle, so it is the most likely to crack under a sharp, direct blow.
Is sapphire crystal worth the extra money?
On a watch you mean to keep, yes. Sapphire is the single feature that keeps the dial looking new for the life of the watch, protecting both the look and the resale value. On a fashion or second watch you will rotate, mineral glass is the sensible choice and the saving is real.
How do I know if my watch has sapphire or mineral crystal?
Check the specification -- a watch with sapphire almost always says so, as it is a selling point. As a rough test, a drop of water beads up more on sapphire, and sapphire feels cooler to the touch and rings differently when tapped, but the spec sheet is the reliable answer. Tissot and the better Citizen models use sapphire; most fashion-quartz watches use mineral.
Can you polish scratches out of a watch crystal?
It depends on the crystal. Acrylic scratches buff out easily at home with polishing paste. Mineral can sometimes be lightly polished by a professional. Sapphire is too hard to polish, so a damaged sapphire crystal is replaced rather than buffed. Our guide on removing scratches from a watch covers each case.
What is an anti-reflective coating on a crystal?
An anti-reflective (AR) coating is a thin layer applied to a crystal -- usually sapphire -- to cut glare and make the dial easier to read. The coating itself can scuff over time even though the sapphire beneath does not; the best watches put the AR coating on the underside of the crystal to protect it.
Which watches at OD's have sapphire crystal?
Our Tissot watches use sapphire crystal across the range, and the better Citizen Eco-Drive models do too -- both built to be kept and worn daily. Browse Tissot watches and Citizen watches.
Do fashion watches use mineral crystal?
Typically, yes. Our fashion-quartz brands -- BOSS, Tommy Hilfiger, Olivia Burton and Vivienne Westwood -- generally use mineral crystal, which suits a style-led watch at a friendly price. It is perfectly appropriate for a watch you will rotate through a collection rather than wear hard every day.
Sapphire vs mineral -- which should I buy?
Buy sapphire if the watch is a keeper you will wear for years and a scratch would bother you. Buy mineral if you are choosing on style or budget, or want a touch more shatter tolerance. In short: sapphire for the watch you will love long-term, mineral for the fashion or second watch.
Is mineral crystal the same as Hardlex or Crystal glass?
They are closely related. Hardlex is one brand of hardened mineral glass, and various makers use their own names for treated mineral crystals. All sit in the same mid-range band -- harder than acrylic, softer than sapphire -- so the practical trade-offs of scratch versus shatter resistance are the same.