1. Quality of the canvassing
The jacket should be fully canvassed by hand. This is hugely important as the canvassing sets the shape of the jacket and determines the final outcome from the very beginning of the making process.
It's easy to check if your jacket is hand-padded, as your cutter would be happy to show you a work in progress. Otherwise, at the first fitting of your suit, take a look inside the fronts and you will see the hand pad stitching on the chest as well as a layer of canvas going all the way to the bottom.