In my books I describe how a garment's details tell so much more about innate quality than the name on the label. Now, the name on this garment's label is pretty good--Yves Saint Laurent--and this particular detail shows why his fame is warranted.
This is a silk bolero from the winter '90 Rive Gauche line. Let's take a look at its pattern matching. This means how carefully the person who sewed it matched up the fabric's printed, or in this case, woven, motifs across openings and seam lines. Doing this accurately takes time and requires careful cutting and piecing of the fabric: top-down perfectionism from the design concept to its realization by a skilled sewing machine operator.
Here we see the front opening of the jacket. Note how the floral and leaf elements link up perfectly. It's the kind of detail most people don't notice, but you should, if you want to train your eye to find the best vintage going.