Here’s the honest truth: as cashmere has gone from an exclusive luxury product to a mass-market luxury product, the quality has suffered tremendously. It’s possible to walk into a J. Crew or even a Costco these days and buy a relatively affordable cashmere sweater, but you’ll get what you pay for. Your “investment” will be useless in all too short a time.

Cashmere is soft because it comes from the hairs on the belly of a goat. They’re exceptionally fine, which makes them exceptionally pleasant to the touch. But here’s the catch: some of these hairs are longer than the others.

As we learned in our video with Luciano Barbera, longer fibers are an essential part of a quality fabric. These days, cashmere’s made with much shorter fibers, by inexpert (or uncaring) weavers in China. This has made a formerly dear fiber affordable, but it’s also made it very difficult to find the good stuff. Even the finest cashmere makers have to fight to get anything worth weaving. Many have given up and decided to coast on their reputations.

This is situation is doubly tricky because low-quality cashmere feels so soft in the store. It may even feel softer than the good stuff, in fact. The reason? Short fibers mean more breakage. Broken fibers fluff out of the fabric, making it soft – think of an angora sweater. It’s the same reason that old t-shirts are softer than new ones.

Broken fibers mean softness, but they also mean stretching, pilling and fuzziness. A sweater, in other words, that starts to look worn out immediately, and wears out quickly.

If you can’t afford to buy $800 sweaters from ultra-high-end makers, there is an easy and affordable answer. Buy vintage. Cashmere, and particularly Scottish cashmere, from before the 1990s cashmere boom, is available at your local vintage shop, flea market, and on eBay. The price is usually no more than $50. The quality is uniformly higher, and it will last many, many years if you care for it. In fact, very high-quality cashmere only gets better with age.

Look for cashmere that feels tightly woven, with a solid feeling, rather than a fluffy feeling. The weave should feel dense, heavy and smooth. A thin cashmere sweater should be warm and solid. Hand wash once a year or so, dry flat, and you’ll have a treasure you can enjoy for a decade or more.

(Previously: A Basic Cashmere Wardrobe for Men, A Quick Guide to Quality Cashmere)