Apart from the single-needle stitch (and fit), there are other hallmarks of a well-made shirt.
Here are some:
A split-yoke with pattern well-matched
There are varying reasons put out to explain why a split-yoke is superior to one that isn't split. The first reason goes something like the shirt-maker will take into account the fact that one's shoulders are not level and thus split to yoke to make each side of the split yoke different in order to account for one's shoulder asymmetry. Second reason is that by splitting the yoke, you're allowing for more stretch in the yoke, and therefore gives you marginally more ability to, well, stretch. Whatever the reason and its veracity, the split-yoke is often regarded as a hallmark of a well-made shirt. Expensive bespoke shirts usually come with a split yoke.
When patterns are matched, it also signifies that more effort went into making the shirt. You'll see that even though my yoke has been split, the lines are matched and still meet at a point.
The Mother-of-pearl button and the crow's foot stitch.
Like with a Mercedes where you don't just expect a sleek silhouette, but also expect the interior to be top-grade, on a shirt, the trimmings are what shirt connoisseurs looks out for -- the Mother-of-pearl buttons being one of them. Whilst one won't mistake a Mercedes for being an Aston Martin just because of an uber-luxurious interior, it does, however, set one Mercedes apart from another. Well, at least to the lady you're sitting with in the back seat. Same with shirts.
The hand-shanked buttons are another detail that helps nudge the shirt into the realm of luxury. On most RTW and even on many bespoke shirts, you'll probably see that the button is sewn nearly flat on the fabric. This can make it relatively harder to button when compared to the hand-shanked button where the button is suspended a couple MM from the fabric via a shank. Easier to grip.
Ahh ... the 'purist' detail. If you peer at how your button has been stitched on the shirt (where the four holes on the button are), chances are that the thread is in a criss-cross shape. Easy, and fuss-free. Shirt purists look for the crow's foot stitch (it's so called because it resembles the foot of a crow) as shown on my shirt below, or for the stitch on the button to run parallel, like this =
Yes, luxury is subtle.
The Gusset
Gussets have traditionally been sewn on the hems to help reinforce against wear and tear at this point. It does take slightly more time to make. It is, after all, one additional step, though every good shirt-maker should do this without any up-charge. Typically a feature of bespoke shirts, but if you waltz into a shop selling branded merchandise, chances are that you'll see the gusset on the shirt.
Finally, for those interested in the construction of my shirt with a one-piece collar ...
