Turn a pair of jeans inside out and you will find a small white tag, usually frayed by the second wash. Most people never read it. Yet that scrap of fabric is a compact biography of the garment, and learning to read it is the quickest way to tell a considered pair of jeans from a disposable one.
Start with weight. Denim is measured in ounces per square yard, and the number tells you how much cloth the mill spent on the fabric. Under 12 oz is light and summery. Between 13 and 15 oz is the everyday heart of the craft. At 21 oz and above, the cloth is stiff as sailcloth and asks for months of wear before it softens. Heavier is not automatically better, but a label that states the weight proudly is a label with nothing to hide. Japanese brands, in particular, treat the ounce figure almost as a signature.
Next, read the fibre line. One hundred percent cotton is the baseline for heritage denim, but the details matter more than the percentage. Look for the origin of the cotton and the loom. A label reading "selvedge" tells you the cloth was woven on a shuttle loom, with a self-finished edge that will not unravel. That is the clue to slower, narrower, more characterful fabric. Some of the finest of it is woven in Faisalabad and Sialkot on Pakistani looms, then shipped to Okayama and Osaka, where Japanese makers cut, sew and finish it. A good label will say so plainly: woven in one place, finished in another. The honesty of that sentence is worth more than any slogan.
Then look at the finishing codes. Words such as "rigid", "raw" or "unsanforized" describe cloth that has not been pre-washed or pre-shrunk, and it will shrink perhaps an inch or two in the first soak. "Sanforized" means the shrinkage has already been controlled. "One-wash" or "stone-washed" tells you the denim has been softened, and with it some of its potential to fade in your own pattern. Neither choice is wrong, but you should know which one you are buying, because the answer decides how you size the jeans and how they will age.
Finally, read the care instructions, which are the maker's quiet advice. Cold water, inside out, hang dry. If the label recommends the opposite, ask yourself why. In Japan there is a phrase, ichigo ichie (一期一会), the idea that each encounter happens only once. A pair of raw jeans is that kind of encounter: the fades you earn belong to you alone, and the label is where the conversation begins.
The next time you hold a pair of jeans in a shop, turn them inside out before you look at the price. The numbers and words on that little tag will tell you who made the cloth, how it was woven, and whether anyone cared enough to say so.