Face That Would Stop A Clock Meaning

(idiomatic) A shockingly attractive face.

Example: 1891, "The Mystery Still Deep: Queer story told by a strange young Englishman," New York Times, 20 Mar., p. 5:
  He described the thug as a very ugly and wicked-looking man, with a face that "would stop a clock".
1927, "Editorial Comment: Thinking Statistically," Educational Research Bulletin, vol. 6, no. 7, p. 142:
  We realize that all women are fair only in theory and that if we arranged them in the order of fairness we should have at one end the face that launched a thousand ships and at the other end the face that would stop a clock.
2004, Barbara Hall, "Bookwise: Questions," Sunday Times (UK), 4 Jul. (retrieved 5 July 2008):
  Archie was an artist, finely chiselled, "the type girls go for like catnip." He . . . was expected to marry an American heiress. But she loved a muscular curate with a face that would stop a clock.
1983, John Cougar Mellencamp, "Pink Houses":
  Hey darlin'
  I can remember when you could stop a clock.