Curious about finish on watch part

[Jon Heron]

I have an economy Invicta automatic titanium watch with a crystal in the back to view the mechanism.
The part that goes around and around, I assume to wind the watch, has a very nice pattern on it that catches the light and looks very sharp when you move it around in your hand, kind of looks like a moving shadow between the lines.
I am just curious how this finish was achieved?
Cheers,
Jon

The pic does not do it justice but you can see what I am talking about.

[EddyCurr]

Is the part marked "NH35A" flat or are those a series of
furrows left either by several passes with one abrasive
object or one pass with multiple abrasive objects operating
at an angular offset to the path of the part as it moves
past the abrasive.

.

[EddyCurr]

Like a variation on ornamental Engine Turning

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[Glug]

I cannot see much of the pattern, but..

You might experiment by mounting a wooden dowel in your drill press or mill. After you square the end up on a file or abrassive paper, coat the tip of the dowel with valve grinding compound or similar. Then you can press the dowel into the work surface and burnish. Maybe by dragging it along, and by canting the work at an angle, you can achieve a similar finish?

I suppose you could also use a metal rod that is harder than the material to be textured.

[RWO]

You can see how Blancpain does it on their mega dollar wrist watches at https://www.youtube.com/watch?v=njcdITiWWyM. Look at about the 6:20 mark. It's not real clear, but there is some kind of abrasive on the bottom of the tool held in the machine's vertical spindle.

RWO

[Jon Heron]

Is the part marked "NH35A" flat

Yes.
Thats it RWO!
Great vid!
Cheers,
Jon

[EddyCurr]

Yes.
Thats it RWO!

Seems this is known as Cotes de Geneve or Geneva Stripes. A
rare instance where an out-of-tram spindle is desireable.

I see that the fancy phrase for engine turning is Perlage Engraving:
'swirls of overlapping circles'.

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[Paul Alciatore]

Eraser/rubber tip with grinding/polishing compound? Make multiple, parallel passes to achieve the lines effect?