Walk along with me now, and see if you see what I do.
First let's note that this little gem was likely a remake using fabric from an earlier garment. I say this because the embroideries are sparse and random, rather than planned to the garment.
The center front meets edge to edge. If we look at the left side, for instance, we can see two vertical rows of stitching. There may be a tape or something behind to help strengthen the fabric to take the strain of the lacing.
At the neckline edge the fashion fabric is folded back to the underside, and is stitched down to create a channel for the drawstring, of tape, that you see still tied. The stitching for this channel is covered by the gimp trim.
The lacing is made of multistrand cord. Its gleam makes me think it may be silk.
This is a detail of the inside of the left shoulder of the garment.
Please be sure click on the photo above and really look at it or you probably won't understand the below.
A: This is actually the underside of the collar, not a part of the shoulder strap. The fashion fabric has been turned to the underside of the collar, turned again to enclose the raw edge, and stitched down. On the exterior, the seam would be hidden by the gimp trim.
B: This is the armscye edge of the shoulder strap, seen from the inside of the garment. The fashion fabric appears to have been turned in once, and then covered by a narrow cream tape or ribbon, which is stitched down along each long edge, apparently with the blue silk thread used elsewhere on the garment.
C: This is the shoulder strap where it attaches to the back piece. You can see that the strap is laid atop the back piece, the raw edge turned under, and hemmed down. You can barely see a line of prick stitching about a quarter inch above. On the outside, this would be the seamline of prick stitching (my guess) that fixed the back piece to the shoulder.
D: This is the upper edge of the back piece, just peeking out from below the shoulder strap. Its raw edge has been turned under too and hemmed down. You can see the continuation of that neckline hem at F.
E: This is the neckline edge of the shoulder strap. Here the fashion fabric has been turned under twice and hemmed down. Thick, isn't it?
F: Here is the neckline edge of the back piece. It's treated the same way.
G: This is the collar seam! The collar appears to be simply brought to the inside of the already finished neckline, the raw edges turned under, and hemmed down. See where the neckline turns? Note how the collar has a little wrinkle there. Was perhaps the collar a later addition to an earlier, plainer jacket? Or did the maker simply not care to fuss with a facing? Given how the rest of the fabric is finished, that would just add bulk.
The garment is, to my mind, happily casually finished, almost ill-thought. It suits me, for some reason, perhaps because I am continually process-challenged as I learn all of these methods, and my mistakes lead to such collar "issues" as we see here.
Next time, we look carefully at the rest of the garment.
Readers, if you take exception to my dissection, I beg you write and let me know what you think. Together we may be able resurrect this puppy!