No products in the cart.
Newsletter
[contact-form-7 id=”4235″ title=”Contact form 1″]
Reading the Movement — Part 3: Decoration Hand vs. Machine, Engraving and engine-turning
If surface finishing is the foundation of movement quality, decoration is its expression. The distinction between the two is precise: finishing improves and perfects the component itself — its planarity, its edges, its surfaces, it can have an effect the quality of movement functioning.
Decoration adds ornament to what is already finished. The two layers are sequential and dependent: no decoration applied over a poorly finished surface will read as quality work, because the underlying defects remain visible beneath it. Decoration does not compensate for insufficient finishing. In haute horlogerie, this principle is a law.
The same diagnostic discipline that applies to finishing applies here. Every decorative technique used in watchmaking can be executed by hand or by machine. The results are similar but not equivalent, and the differences are readable — by an expert eye, under magnification, or directional light, or in some cases without any magnification at all. This is a technique-by-technique guide to reading those differences.
Côtes de Genève and perlage occupy an ambiguous position in the decoration/finishing taxonomy — both are applied to visible surfaces for aesthetic effect, which places them logically within this chapter, but both also have functional origins and direct relationships with the finishing quality of the components they decorate.
For this reason they were treated in Part 1, alongside anglage and flanc preparation, so you should should refer to Part 1 of this topic for the full treatment of both techniques, including the hand vs. machine telltales for each.
Gravure — Engraving
Engraving in watchmaking serves two distinct functions:
- As an identification tool it carries calibre references, manufacturer marks, serial numbers, and hallmarks — the functional minimum present on virtually all Swiss movements.
- As a decorative technique it personalises and embellishes the movement, creating motifs on plates, bridges, and cases that are specific to a timepiece.
Four methods exist.
A hand-engraved Audemars Piguet movement
The oldest is Hand engraving — gravure en creux — is the oldest decorative technique in watchmaking and the one against which all other methods are measured. The engraver cuts the design directly into the metal with a burin, a small hardened steel tool ground to a specific profile. No template guides the cut — the design exists first as a traced outline on the component surface, and then as a series of incisions made entirely by hand, under a binocular loupe magnifying up to 35 times.
Lange 1 Tourbillon-haned-engraved bridges, chatons with screws, impeccable wheels, anglage, perlage blued screws, as good as it gets
Each engraver maintains a personal assortment of approximately twenty burins, individually shaped to their own technique and hand dimensions — onglettes for fine, flowing cuts; flat échoppes for broader strokes; gouges for curved recesses. A finely hand-engraved 1800`s minute repeater pocket watch
The characteristic quality of hand engraving under magnification is that the metal is polished as it is cut — the burin displaces and burnishes the material simultaneously, producing a surface quality that no machine replicates.
Another telltale characteristic of hand engraving is directionality: the cut shows the movement of the tool, the slight organic variation of the hand-guided cut, the way a line quickens or slows with the engraver’s pressure, is precisely what gives the work its character. Scroll work and volutes — curved, spiralling motifs — are either impossible or visually inferior when produced mechanically. Their presence in a hand-engraved movement is an immediate quality marker.
Hand engraving on a Girard Perregaux Chronograph
Hand engraving mid-range quality
Industrial engraving
Inpeccable hand-engraving on a Glashutte Original PanoMaticLunar movement engraving
Next on a timeline we have Pantograph engraving which exists in two distinct generations that produce different results.
The traditional pantograph uses an articulated arm guided by a metal template — the chablon — to reproduce a master design at the desired scale, with a diamond point, burin, or cutter tracing the template geometry onto the component surface. The operator controls the tool’s pressure and movement, which introduces a degree of human engagement absent from fully automated processes — the result retains some of the directional character of hand work, particularly on curved or complex motifs.
Traditional pantograph (hand) engraving – it still has that human touch
The modern CNC pantograph operates on an entirely different principle: the articulated arm is replaced by a numerically controlled rotating cutter that advances step by step across the component surface, executing the programmed design with the same geometric precision as any other CNC process.
The visual result is indistinguishable from direct CNC engraving — perfectly uniform depth, consistent edge geometry, no tool directionality. The traditional pantograph belongs in the artisanal category with appropriate qualification; the CNC pantograph belongs with industrial methods.
Laser engraving sweeps the surface with a CNC-guided light beam, removing material with absolute geometric precision and producing edge profiles that are physically impossible to achieve by any mechanical cutting tool.
The diagnostic telltale is twofold: the geometric perfection of the cut itself — perfectly uniform depth and edge geometry across the design, without any variation — and the thermal signature left by the laser on the surrounding metal.
Perfect CNC engraving on the case-edge of a Lange & Sohne Langematik Perpetual Calendar
Where the beam has grazed or passed close to an edge, a slight discolouration or surface oxidation is often visible under magnification — the metal has been locally heated rather than cut. On high-grade movements this residual burn mark is unacceptable and will be finished away; on industrial production it frequently remains. Its presence under a loupe is an unambiguous indicator of laser execution.
A laser-engraved Glashutte Original Panoinverse limited edition 2023
CNC machine engraving produces letters and numerals with mechanically perfect geometry — consistent depth, perfectly regular spacing, no variation between characters.
CNC-Engraved movement inscriptions on an Audemars Piguet caliber
Surface texture of the cut walls CNC engraving uses a rotating cutter that leaves microscopic tool marks on the walls of the cut — fine parallel striations following the direction of the cutter’s rotation, visible under magnification. Laser engraving produces smooth, almost glassy cut walls where the material has been vaporised rather than mechanically removed. This is the most reliable single telltale.
An older engraving on a Longines Swissair showing tool markings
Edge profile A CNC cutter produces a V or U profile determined by the tool geometry — clean and consistent but with a mechanical regularity. Laser produces a slightly tapered edge profile where the beam energy decreases with depth, giving the cut a characteristic narrowing toward the bottom that differs from any mechanical tool geometry.
Thermal signature on a laser engraving
Thermal signature Laser engraving heats the metal locally rather than cutting it mechanically. Under magnification this produces two readable effects: a slight discolouration or oxidation at the cut margins where the beam has grazed the surrounding surface, and in some cases a darkening of the metal within the cut itself where combustion residue has not been fully cleaned away.
CNC engraving produces no thermal effect whatsoever — the metal is cold-cut and the cut walls retain the natural colour of the base material throughout. The presence of darkened metal at or within the engraved line is therefore a definitive indicator of laser execution.
An Acid Engraved back on a Oris Nordzee
Chemical engraving is the least expensive of all engraving methods and is used accordingly on the lowest grade of production. The component is coated in a UV-sensitive protective varnish, a negative film of the desired design is applied and irradiated, and the piece is then immersed in acid which attacks only the exposed metal. The concentration of acid determines the depth of the cut — typically a few tenths of a millimetre.
The diagnostic telltale under magnification is the edge profile: acid bites into the metal isotropically, meaning it attacks in all directions simultaneously, producing slightly irregular, rounded edge profiles where the acid has undercut the varnish boundary.
Neither the clean V or U profile of a CNC cutter nor the tapered vaporisation profile of a laser is present. The base of the cut is also irregular in texture — the acid leaves a characteristically matte, slightly pitted surface rather than the smooth walls of laser work or the striated walls of CNC. On finished movements the acid residue is cleaned away, but the rounded edge profile and irregular cut base remain readable under a loupe and identify chemical engraving unambiguously.
The diagnostic distinction between industrial and hand engraving is readable at the level of the cut itself. Machine and laser engraving produce uniform depth and perfectly regular edge geometry that is physically impossible to achieve by hand
Guillochage — Engine Turning
Guillochage is one of the most technically demanding decorative techniques in watchmaking and one of the most frequently misrepresented in marketing. It is named — according to tradition — after a worker named Guillot who developed the technique, and it flourished particularly in the early 19th century. The principle is a geometric combination of straight lines and curves, cut into the metal surface with a burin guided by a rose engine or straight-line engine, producing patterns of extraordinary complexity and optical depth. A Guillochage – Engine turning machine
The critical distinction for collectors is between true guillochage “a main”, coinage, and CNC-milled imitation.
True guillochage is a cutting process. The rose engine or straight-line engine removes material — the burin cuts the metal, and the pattern is determined by the geometry of the machine’s guide system. The guillochage machines are no longer manufactured. The few specialist ateliers that still practice hand guillochage use antique machines, often 100 or more years old, restored and maintained by the guillocheur themselves — a craft that requires as much mechanical knowledge as artistic skill.
The pattern produced by a rose engine has a characteristic centre-point geometry and a depth of cut that catches directional light in a way that CNC work cannot replicate. Under magnification, the individual cuts of the burin are visible as clean, V-profile channels with consistent geometry across the full surface.
The term guillochage à main — literally “by hand” — requires qualification. The rose engine and straight-line engine are machines, and the pattern they produce is determined by their mechanical geometry. What the designation refers to is the irreducible human element in the process: the operator controls the indexing between each pass, the pressure of the burin against the surface, the depth of each cut, and the sequencing of the pattern. No programme executes these decisions — they are made continuously, by hand and eye, throughout the work. Guillochage on a Breguet dial
A single dial can require hundreds of individual passes, each one dependent on the quality of the last. The slightest error in indexing or pressure is visible in the finished pattern and cannot be corrected without restarting from the blank.
The machine provides the geometric guide; the skill of the guillocheur determines whether the result is extraordinary or merely adequate. This is why the antique rose engines — no longer manufactured, maintained and restored by the craftsmen who use them — are considered irreplaceable. The machines are the instrument. The hand is the musician.
With Guillochage a main, the work begins with a flat, annealed blank — typically gold, silver, or brass. A graver or fly-cutter removes metal in lines of controlled depth and pitch; the operator indexes, advances, and repeats until the full field is complete. Clean intersections and constant line spacing are critical. Sub-dials and apertures are either cut first, with the pattern fading out at the edges, or the guillochage is completed before the holes are punched, with careful support to prevent the blank from buckling under the cutting pressure.
Once the guillochage is complete the dial blank undergoes surface preparation before printing, usually a light humid sandblasting after guillochage, creating a fine matte ground without impact on the cut pattern. This preparation ensures that the subsequent galvanic treatment — typically rhodium or gold plating — adheres correctly and does not fill or distort the engraved channels.
Traditional dial printing then follows: applied indices, hour markers, and brand signature are added after plating.
On flinqué enamel dials — translucent enamel is fired directly over the guillochéd surface allowing the engraved pattern to remain visible through the glased – vitreous – enamel layer.
Each step depends on the quality of the previous one — a guillochéd blank that is not perfectly flat or where the metal does not have a perfectly even composition, will produce a distorted pattern; a surface not correctly prepared before galvanoplastie will show adhesion failures; printing applied over an inadequately plated surface will be blurred.
Piaget Altiplano flinqué et Guilloché
The quality requirements for genuine guillochage are precise: the burin must be calibrated to the material and desired depth; the burin height must be consistent to ensure pattern regularity; the piece must be perfectly flat so the guide contacts the surface equally around its full circumference. The final step is polishing, which brings the characteristic brilliance of the technique.
Coinage on a dial
Coinage is a compression process. The metal is struck – minted like a coin – under pressure with a hardened die, displacing rather than removing material. The visual result can appear similar to guillochage at a casual inspection, particularly on dials where the pattern is applied to the full surface. Under magnification the distinction is clear: coined patterns show slight edge compression at the channel margins where the metal has been pushed aside, and the channel profile is rounded rather than V-cut.
The light response differs accordingly — coinage reflects more diffusely than cut guillochage where edges are usually sharper.
A well coined dial – Patek Philippe ref. 4997
CNC milling produces guillochage-like patterns with absolute geometric regularity — perfectly consistent spacing, depth, and angle across the full surface. This regularity is, paradoxically, the telltale: hand-guided guillochage shows the subtle variation of the machine’s mechanical engagement that no CNC programme replicates. The pattern of a rose engine has an organic quality to its geometry, particularly visible at the centre point, that CNC work lacks.
When a guillochage a main is executed perfectly, it is difficult to differentiate from a well executed CNC guillochage….
to be continued in the next post – see you soon