Arcs inscribed on the dial to catch and scatter light differently depending on how it falls on them, effectively mimicking how the asbestos fibres work in tiger's eye.

Very difficult to get it precisely right though, and I think this is what they concentrated on rather than exact alignment of each panel. Owners will have seen how the dials can look a bit flat in some lights, and if they got the arcs wrong, this is how they would appear in most conditions. Thankfully, they DID get it right and we have some of the most distinctive Heuer dials as a result.