Cashmere

Cashmere is the soft downy undercoat combed or shorn from cashmere goats, then dehaired, a critical mechanical step that separates the fine down (19 microns or less, top grades 14 to 15.5) from coarse guard hairs that run 50 to 100 microns. Only about 30 to 50 percent of the raw fiber survives dehairing as usable cashmere.

With cashmere, your comfort is decided almost entirely by processing quality, not the species. Fine cashmere down is well below the roughly 30-to-32-micron threshold at which fibers stiff enough to mechanically jab your skin's nerve endings cause prickle, the itch that most people mistake for an allergy. But it takes only a few overlooked guard hairs to make luxuriously soft cashmere scratch and irritate, the so-called prickle factor, and two cashmeres with identical average microns can feel completely different depending on how well those coarse hairs were removed. Cheap cashmere is usually cheap because it skipped thorough dehairing. As with all goat and sheep fibers, an itch reaction is a physical, non-immune irritant contact dermatitis, not a true allergy.

Buy on fineness and dehairing quality, not just the word cashmere: look for fiber around 15 to 16 microns and OEKO-TEX STANDARD 100 certification for dye and finish safety.

Cashmere goats graze close and can degrade fragile grassland, and the very low yield per animal means each sweater represents many goats.