Can anyone tell me more about this dial? 1971 Perpetual 1002...

[bluedevil]

I have been scouring available resources looking for more information about the dial on my 1971 perpetual 1002. I cannot find any reference to the angular pattern on the face which is made up of thousands of small lines and rectangles of varying deep blue shades. My father gave it to me some time ago and indicated some degree of uniqueness. I love the watch and get a fair number of compliments on the beauty of the dial. Simply wondering how common or rare this is, especially since I have found just one photo online among thousands that clearly shows the same pattern. (And for you aficionados, please excuse the scratches, etc. - I wear it daily and it needs to be serviced!)

Thanks for any insight anyone can provide.