Watch materials and finishing explained

Case materials at a glance

Values are approximate and depend on the alloy and the manufacturer.

Stainless steel: the backbone of the Swiss watch

Steel is by far the most common case material. It is strong, resists corrosion, can be mirror-polished or brushed and keeps its shape for decades. That steel sports watches are now among the most sought-after luxury watches goes back to the history of the tool watch – and to Audemars Piguet's decision in 1972 to launch the Royal Oak as a luxury watch in steel.

316L – the industry standard

The austenitic steel 316L contains roughly 16–18% chromium, 10–14% nickel and 2–3% molybdenum. The "L" stands for low carbon, which prevents intergranular corrosion. 316L comes from medical technology, is easy to machine and is used by almost every Swiss brand, from Omega to TAG Heuer and Longines.

904L – Rolex "Oystersteel"

904L has more chromium (about 20%), much more nickel (about 25%), around 4.5% molybdenum and some copper. It resists salt water better and takes a deep, slightly warmer polish, but it is harder to machine and wears tools faster. Rolex began using 904L in the 1980s; today all its steel models are made of it, under the name Oystersteel.

Other steel variants

• In-house alloys: Omega uses its own recipes such as O-MEGASTEEL for selected models.
• Anti-magnetic cases: soft-iron inner cages shield the movement from magnetic fields, classically in the Rolex Milgauss or the IWC Ingenieur.

Examples

• Rolex Submariner – Oystersteel (904L), the archetypal dive watch.
• Omega Speedmaster Moonwatch – 316L, brushed case with polished bevels.
• Audemars Piguet Royal Oak – steel as a luxury material, famous for alternating polished and brushed surfaces.
• Patek Philippe Nautilus 5711/1A – the best-known example of a steel watch trading above gold models on the secondary market.

Gold: value, colour and in-house alloys

Pure 24k gold is far too soft for a watch case. Swiss watches therefore almost always use 18k gold: 750 parts fine gold per 1,000. The remaining 25% – mostly silver, copper or palladium – decide colour and hardness.

Proprietary gold alloys

Because the copper in rose gold can oxidise and fade, several brands have developed their own alloys:

• Rolex Everose (since 2005) – 18k rose gold with platinum to stabilise the colour. Rolex runs its own foundry and alloys its gold in-house.
• Omega Sedna Gold (since 2013) – gold, copper and palladium for a long-lasting red tone.
• Omega Canopus Gold – an in-house white gold with high lustre, without rhodium plating.
• Hublot Magic Gold (since 2011) – scratch-resistant 18k gold: porous boron carbide ceramic is infused with molten gold under high pressure.

Swiss hallmarks

Swiss gold cases carry a fineness mark (such as "750" or "18K"), the manufacturer's responsibility mark and the official assay mark – for gold, the head of a St Bernard dog. Missing or inconsistent hallmarks are an important warning sign when buying; see also how to spot a fake watch.

Platinum: the most discreet precious metal

Platinum is rarer than gold, much heavier and usually used as Pt 950 (95% platinum). A platinum case feels noticeably heavier than the same case in gold. It looks similar to white gold or steel but cooler and deeper.

Platinum is relatively soft but tough: a scratch displaces the metal rather than removing it. Over time a fine matt patina forms, which many collectors like. For manufacturers it is demanding – hard to machine, hard to polish and tough on tools.

• Rolex Day-Date in platinum – Rolex reserves the ice-blue dial for platinum models.
• Rolex Daytona 116506 – platinum case, chestnut-brown Cerachrom bezel and ice-blue dial.
• Patek Philippe – many platinum models carry a small diamond in the case side at 6 o'clock as a discreet mark.
• Hallmark: "PT950" or "950 Pt" on the caseback or lugs.

Titanium: light, strong, skin-friendly

Titanium is about 45% lighter than steel, highly corrosion-resistant, non-magnetic and very skin-friendly. Its natural tone is a little darker and greyer than steel. In 1980 IWC made one of the first titanium chronographs, for Porsche Design.

• Grade 2 (commercially pure): softer, easy to machine, matt grey look, scratches more easily.
• Grade 5 (Ti-6Al-4V, with 6% aluminium and 4% vanadium): much harder and stronger, can be polished and looks closer to steel. The standard for high-end sports watches.

Examples

• Tudor Pelagos – dive watch with titanium case and bracelet.
• Rolex Deepsea Challenge (2022) – the first Rolex in its in-house grade 5 alloy "RLX titanium".
• Richard Mille – grade 5 titanium, often combined with carbon.

Ceramic: scratch-proof and colourfast

High-tech ceramic in watches is mostly zirconium oxide (ZrO₂). It is several times harder than stainless steel, practically scratch-proof in daily use, light, skin-friendly and keeps its colour for decades under UV light and salt water.

How a ceramic case is made

1. Fine ceramic powder is mixed with pigments and a binder.
2. The mix is injection-moulded (CIM, ceramic injection moulding).
3. The binder is burnt out and the part is sintered at around 1,400–1,500 °C. It shrinks by roughly 20–25%, which the mould must allow for exactly.
4. Machining and polishing are then only possible with diamond tools.

Examples

• Rado – the ceramic pioneer; the Rado Integral of 1986 made high-tech ceramic known in watches. Later came "plasma ceramic" with a metallic sheen but no metal.
• IWC Da Vinci ref. 3755 (1986) – one of the first chronographs with a ceramic case.
• Rolex Cerachrom (since 2005) – ceramic bezels with engraved, platinum-coated numerals, first on the GMT-Master II.
• Omega Speedmaster "Dark Side of the Moon" (2013) – case entirely in black zirconium oxide ceramic.
• Swatch Bioceramic (since 2021) – ceramic mixed with bio-sourced plastic, known from the MoonSwatch.

Note: ceramic is hard but brittle. A fall onto a tiled floor can crack a bezel or case, and a replacement part is usually the only fix.

Carbon: high-tech from motor racing

Carbon in watches is a composite of carbon fibres and resin: extremely light, very strong and unmistakable in look. Swiss watchmaking uses several processes:

• Forged carbon: short fibres pressed under heat and pressure create a marbled structure – every case is unique.
• NTPT carbon (North Thin Ply Technology): hundreds of ultra-thin, offset layers of fibre create the typical wave pattern, known from Richard Mille.
• Carbotech (Panerai): carbon fibres in a PEEK polymer matrix, matt black with a fine layered structure.

Examples

• Audemars Piguet Royal Oak Offshore "Alinghi" (2007) – made forged carbon known in watchmaking.
• Richard Mille RM 35-01 – one of the first watches with an NTPT carbon case.
• Panerai Luminor Submersible Carbotech PAM 616 (2015).
• Hublot Big Bang – carbon combined with rubber and ceramic.

Drawback: deeper scratches or chips can hardly be repaired; a damaged part is replaced.

Sapphire crystal: the standard of the luxury watch

Sapphire crystal is not glass but synthetic corundum (aluminium oxide, Al₂O₃) – chemically the same as natural sapphire. With a Mohs hardness of 9 it is one of the hardest materials after diamond and practically scratch-proof in daily use.

Production

Synthetic sapphire has been made since the early 20th century by the Verneuil process (flame fusion); today crystal-growing methods such as Kyropoulos are also used. Discs are cut from the crystal with diamond saws, then ground, domed or faceted and polished. Because sapphire is so hard, this takes time and wears out many diamond tools – which is why a domed or box sapphire crystal is expensive.

Variants

• Anti-reflective coating: on one or both sides. On the inside it stays intact; on the outside it can show wear over time.
• Cyclops lens: Rolex's date magnifier, introduced in 1953, magnifies about 2.5 times.
• Box sapphire: high-domed in the style of historic acrylic crystals, for example on vintage re-editions.
• Sapphire caseback: shows the movement and its decoration.
• Sapphire cases: fully transparent cases, for example from Richard Mille or Hublot – extremely complex to make.

Alternatives

• Hesalite / acrylic: shatter-proof and easy to polish, but scratches easily. The Omega Speedmaster Moonwatch is traditionally offered with Hesalite because it does not splinter if it breaks.
• Mineral glass: hardened glass, cheaper and less scratch-resistant than sapphire; rarely used in luxury watches today.

Lume: from radium to Super-LumiNova

Luminous material makes hands and indexes readable in the dark. It also tells a lot about the age and originality of a vintage watch.

Swiss makers and examples

• RC Tritec (Teufen, Appenzell) – has produced Super-LumiNova since 1998, based on the Japanese Luminova technology. Well-known shades are C3 (greenish, very bright) and BGW9 (blue-white).
• Rolex Chromalight (since 2008) – in-house lume with a blue glow and long duration, introduced with the Deepsea.
• mb-microtec (Niederwangen, Bern) – makes tritium gas tubes ("trigalight"), used by Swiss brands such as Ball and Luminox.

What it means for value: on vintage watches, an even, original tritium patina on hands and dial is highly sought after. Relumed indexes or mismatched replacement hands often lower the collector value considerably.

Finishing: where craftsmanship shows

Two watches in the same material can look completely different depending on how their surfaces are finished. There are three areas: case and bracelet, dial and movement.

Case and bracelet

• Polishing: a mirror shine. With "black polishing" a surface looks deep black from certain angles – top craftsmanship that can take hours per part.
• Satin brushing: fine parallel lines for a silky matt look that hides light scratches.
• Sand- or bead-blasting: an even, grainy matt surface, popular for titanium and military watches.
• Bevelling: angled, polished edges. The interplay of brushed surfaces and polished bevels defines the Audemars Piguet Royal Oak.
• PVD and DLC: ultra-thin coatings applied in a vacuum for black, gold-coloured or other tones and more scratch resistance.

Dial

• Guilloché: patterns engraved with hand-operated rose engines and straight-line machines, such as "Clous de Paris" at Breguet and Patek Philippe or the "Tapisserie" pattern of the Royal Oak.
• Sunburst: a radial finish that reflects light from the centre outwards.
• Grand feu enamel: glass powder fired several times at over 800 °C, also with techniques such as cloisonné and champlevé. The colours stay unchanged for centuries.
• Galvanic treatment and lacquer: for coloured dials, often with several coats of lacquer.

Movement

• Côtes de Genève: parallel wave stripes on bridges and rotor.
• Perlage: small overlapping circles on the main plate.
• Snailing (colimaçon): a spiral finish, often on wheels.
• Hand bevelling (anglage): polished 45° edges on bridges; sharp inward angles can only be made by hand.
• Flame-blued screws: steel screws are heated to around 290 °C until a deep blue oxide layer forms.
• Rhodium plating, gilding and engraving: protection and decoration for movement parts.

Geneva Seal (Poinçon de Genève): introduced in 1886, this hallmark requires movements made and assembled in Geneva with strict rules for the finishing of every part. It is found, for example, at Vacheron Constantin, Roger Dubuis and Chopard L.U.C.

Manufacturing: from blank to finished watch

Modern Swiss manufactures combine high-tech machines with handwork. These are the most important processes:

Case making

• Stamping / die forging: a steel blank is pressed into shape in several stages under high pressure. This compacts the metal structure and makes the case especially resistant.
• CNC milling and turning: computer-controlled machines cut cases, bezels and bracelet links to hundredths of a millimetre.
• Investment casting (lost wax): mainly for precious metals and complex shapes.
• Metal and ceramic injection moulding (MIM, CIM): for complex parts in metal or ceramic.
• Laser welding and engraving: for caseback engravings, serial numbers and fine joints.

Movement making

• Décolletage: Swiss-type automatic lathes from the Jura make arbors, pinions and screws in large numbers – a Swiss speciality.
• Wire EDM: an electrically charged wire cuts contours into hard metals, for example for wheels and levers.
• Stamping and fine blanking: for plates, bridges and hands.
• Silicon technology: parts are etched from silicon wafers as in the semiconductor industry. Silicon is light, non-magnetic and needs no oil. Milestones: Ulysse Nardin Freak (2001), Patek Philippe Spiromax hairspring (2006), Omega Si14 (2008), Rolex Syloxi (2014).

Assembly and testing

• Assembly: watchmakers fit movement, dial, hands and case; for complications often entirely by hand.
• Water-resistance tests: pressure and vacuum tests, for dive watches often with overpressure beyond the rated depth.
• Chronometer test (COSC): 15 days in five positions and at three temperatures, with an average daily rate of −4/+6 seconds.
• METAS Master Chronometer: tests the finished watch, including 0/+5 seconds per day and resistance to magnetic fields of 15,000 gauss – for example at Omega and Tudor.

What does "Swiss Made" mean? Since 2017 at least 60% of a watch's manufacturing costs must arise in Switzerland. The movement must be Swiss, the watch must be cased up and finally inspected in Switzerland, and the technical development must take place there.

Material and value: what matters for an estimate

• Steel sports models from Rolex, Patek Philippe or Audemars Piguet often command higher premiums on the secondary market than comparable gold models because demand is greater.
• Gold and platinum have a metal value that sets a floor – but for sought-after models the market price is usually far above it.
• Original condition is decisive: an over-polished case with rounded edges loses a lot of value compared with an untouched one. More in our guide to watch condition.
• Lume and dial: original tritium with an attractive patina or a "tropical" dial can multiply the value of a vintage watch; service dials lower it.
• Ceramic and carbon are hard to repair, so damage weighs more heavily in an estimate than on steel.
• Rare materials and alloys, such as a platinum Daytona or early ceramic and titanium models, are especially sought after by collectors.

Technical terms are explained in our watch glossary. Want to know what your watch is worth? Upload photos for a free estimate.