Two tests: visibility, regularity. On a machine sewn shoulder, you generally cannot readily see the stitches. Â Take the coat and look at the interior of the armhole. Â If the diameter looks "clean", it is likely machine sewn, in a manner similar to (say) a trouser side seam. Â All you see is a "valley" where the two pieces of cloth meet, and the seam is hidden underneath. Â If you tug at the seam, you will see stitches, however, and they will look very tight, very close together (almost no gap) and very regular. On a hand-stitched shoulder, you will see a ring of small stitches, with thread clearly visible, perhaps 1/16" apart. Â You will also see little dimples in the lining, similiar to the way a pick stitch looks on a lapel facing. If you look carefully, you will see that the spacing and the size of each stitch are not uniformly perfect.