Reference Guide · Updated on 9 August 2026 · Watch Guide Team

Casio and digital watches: why they’re still going from strength to strength

From the indestructible G-Shock to vintage steel models: which Casio watches are worth buying and why they last for decades.

Glass: sapphire, mineral or acrylic

The sapphire is hard 9 on the Mohs scale: Only a diamond or materials containing corundum can scratch it, which is why it’s the best choice if you’re using the watch every day. The mineral (hardness 5–6) can be scratched by sand, keys or cement, although it withstands a single impact better without chipping. The Hardlex Seiko’s is a hardened mineral, somewhere in between. The acrylic It gets scratched just by looking at it, but you can polish it at home with polish in two minutes, giving it that warm, domed look of vintage watches. An anti-reflective coating on the inside makes the dial much easier to read than one on the outside, which wears off.

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Straps and bracelets: the most cost-effective change

Changing the strap transforms a watch for €20–40 and is the best value-for-money upgrade there is. Measure the width between antlers (18, 20 and 22 mm are the most common) and choose according to your needs: steel for everyday use, skin for washing (never with water), rubber or FKM for sport and summer, and NATO made of nylon for a military look and quick changes. Look for pins made of quick release (quick-release) so that no tools are required. With steel bracelets, the detail that sets the good ones apart from the mediocre ones is the micro-adjustable fastening, which allows you to fine-tune the fit when your wrist swells in the heat.

Which watch is right for each occasion?

The classic rule still holds true: the more formal the occasion, the more understated and simple the watch should be. For suit, a 36–40 mm case, a slim profile that fits under the wrist, a clean dial and a leather strap. For office and diary, an elegant sports watch measuring 38–41 mm with a steel bracelet covers all the bases. For sport and water, a 200-metre diver’s watch or a rugged digital watch. And for to travel, a GMT watch lets you keep track of two time zones at a glance. If you’re only going to own one watch, a 39–40 mm three-hand model with 10 ATM water resistance and an interchangeable bracelet is the most versatile option available.

Value and depreciation: which watches hold their value

Almost all watches are an expense, not an investment, and it’s best to buy them with that in mind. That said, there are clear patterns: models from brands with a rich history and limited production runs retain their value better on the second-hand market, whilst fashion brands lose between a 60 and 80 per cent as soon as they leave the shop. Affordable watches with an established reputation (the classics from Seiko, Casio or Orient) rarely fall much below the initial price range because their starting price is already low. The paperwork, the box and the condition of the strap affect the selling price more than people realise.

Luminescence: Super-LumiNova and LumiBrite

Modern luminescent paint is not radioactive: it is a phosphorescent material that absorbs light and gradually releases it. Super-LumiNova (Switzerland) and LumiBrite (Seiko) are the models, with variants such as the bluish BGW9 or the greenish C3, which is the one that shines the brightest. What makes the difference in practice is not the paint brand but the layer thickness: that’s why a €150 Seiko can outshine a €1,500 Swiss watch. With diving watches, check that the bezel at 12 o’clock and the minute hand – which is the one that counts underwater – are also luminescent.

How to buy a watch without being ripped off

Four things to check before paying: that the salesperson whether it is the manufacturer or an authorised distributor (on marketplaces, check who is shipping the item and who is invoicing); that the warranty that it is the brand’s official specification in Spain and not just that of the seller; that the specifications advertised match the official profile from the manufacturer, particularly crystal and ATM models, as these are where claims are most often exaggerated; and ensure the price isn’t significantly below market value, which is a common sign of a replica. Keep the box, paperwork and receipt: with watches, these add to the value should you ever sell it.

All Casio products and digital watches (64)

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Frequently asked questions about Casio watches

Can I go for a swim in the sea whilst wearing a diving watch?

Yes: a watch rated to 20 ATM and certified to ISO 6425 is designed for just that. Rinse it with fresh water when you come out of the water, as the salt crystallises on the crown and bezel and eventually corrodes the gaskets. And always check that the crown is screwed down before going into the water.

Why do Swiss movements cost more?

It’s about the finish and the regulation, not raw accuracy: a Japanese quartz watch costing €60 is more accurate than almost any Swiss mechanical watch. What you’re paying for is craftsmanship, quality control, the materials used in the movement, and a service network that will still be repairing it twenty years from now.

What are the hands and buttons on a chronograph used for?

The top button starts and stops the stopwatch; the bottom one resets it. The large central hand counts the seconds being timed, and the small counters tally the minutes and hours, whilst the small seconds hand on the dial indicates that the watch is running. Don’t leave it running all day: it uses up the battery or power reserve unnecessarily.

What does it mean for a watch to be ISO 6425-compliant?

It has passed the standardised tests for diving watches, not just the pressure test. It can be recognised by the word ‘DIVER’S’ printed on the dial next to the depth marking; without this marking, it is a water-resistant watch but not a certified diver’s watch.

How much do I need to spend on a Casio watch?

It depends on how you plan to use it: there are good options in the entry-level range, as well as advanced models that are only worth the extra cost if you’re going to make the most of their features. Check the criteria in this guide, work out how you’ll actually use it, and compare the current price on Amazon before making a decision.

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