This type of cable has been available from a New York City
supplier, Myron Tobak, for many years. I remember buying some in
the late 70's, before David Yurman's appearance on the scene.
Now that you mention that, it rings a distant bell. This suggests to
me that it would be an important subject,,,, that of what truly
qualifies as a copyright infringement.
Judging from the responses and indeed my own concept of what
constitutes the Yurman look (...as an example, one which is quite
distinctive even to non jewelers) the concensus might be that fat
cable is the look. But as you say the cable was commercially
available beforehand. I wonder how the court sees it. Is it merely
fat cable or the combination of cable and finials? Or some other
aesthetic that's involved?
I have no clue how to go about researching court rulings relating to
this. I would hope to find a reliable definition, the doctrine of "I
know it when I see it" is perhaps too subjective and risky. Again I
cite Yurman only as an example, it could be Boin, Dunay or anybody.
If someone wanted to explore cable designs it would be very important
to know where the line is that shouldn't be crossed. One might view
that as "how close can I go and get away with it" or "what do I need
to avoid to maintain my integrity". I see a distinction there, the
first suggests an intent to copy, the second suggests honoring the no
infringement ideal in a good faith manner.