From around the net:
The white ones are Oscar de la Renta and Pnina Tornai
They only used striped fabric cut on the diagonal, not spiral seams :-)
This one does use spiral seams but only on top!
And that links to a doll pattern for sale:
Not sure if I've shared this before. There's Farrah Fawcett in a white gown that is the ideal spiral shape.
Here's a spiral seams wedding dress, called "Rae" by Priscilla of Boston
For some really pretty spiral skirts and dresses, check out the brand "Sacred Threads" on ebay.