Cashmere Grading Explained Micron, Fibre Length, Ply and Why Cheap Cashmere Pills

Cashmere is the most misunderstood word in knitwear. It describes a fibre, not a quality; a $60 cashmere sweater and a $1,200 one are made from the undercoat of the same species of goat. The difference lies in how that fibre is graded, dehaired, spun and knitted — and every one of those steps can be judged if you know the vocabulary. This guide explains the grading system, why length matters as much as fineness, and what the numbers on a label actually mean.

Where cashmere comes from

Cashmere is the fine downy undercoat that cashmere goats grow for winter and shed in spring. Herders comb it out by hand; each goat yields roughly 150–250 grams of raw fibre a year, of which perhaps half survives dehairing. It takes the annual yield of three to four goats to make one sweater, which is the fundamental reason genuine cashmere is expensive.

The coldest regions produce the best fibre. Inner Mongolia (China) and Mongolia supply the majority of the world's fine cashmere; goats there endure winters of −40°C and grow long, fine down. Afghanistan and Iran produce larger volumes of coarser fibre used in lower-priced knitwear and blends.

The three grades

Two numbers define a grade. Diameter, measured in microns, determines softness: below about 15.5 µm the fibre cannot be felt as individual hairs against the skin, which is the physical basis of "soft". Length, or staple, determines durability: longer fibres have fewer ends per metre of yarn, so fewer ends work loose to form pills. The two are not the same thing. Short, fine fibre feels wonderful in the shop and pills in a fortnight — and that is precisely the product that gives cheap cashmere its reputation.

Dehairing

Raw combed cashmere is a mixture of fine down and the goat's coarse outer guard hairs, which are 40 µm or more and feel like bristle. Dehairing separates them mechanically, and it is expensive and imperfect: the more passes through the dehairing machine, the more guard hair is removed, and the more fine fibre is lost with it. Cheap cashmere is under-dehaired. Look closely at the surface of a sweater: stray shiny, straight hairs among the soft down are guard hairs, and they mean the mill economised.

Spinning and ply

Cashmere is almost always woollen-spun — the fibres left jumbled rather than combed parallel — to trap air and preserve loft. The quality of spinning shows in the evenness of the yarn: a well-spun 2-ply cashmere is uniform along its length, without thick and thin patches.

Ply is the number of single strands twisted together. 2-ply is the standard for quality: the two strands support each other, the twist locks fibre ends in, and the yarn is even. Single-ply (sometimes marketed as "1-ply" or simply not mentioned) is lighter and cheaper but less durable. Heavier knits use 4-ply, 6-ply or more — William Lockie in Hawick is known for tightly knit 4- and 6-ply cashmere that lasts decades. Ply is not the same as thickness: ply tells you how the yarn is built, gauge tells you how densely it is knitted.

Gauge and weight

The classic luxury cashmere sweater is knitted at 12-gauge in 2-ply yarn, giving a fabric that is dense, warm and drapes well. Lighter 16- to 21-gauge cashmere is used for fine layering pieces; 7-gauge and below for chunky winter knits in multi-ply yarn. What matters is density: a 12-gauge sweater in a proper 2-ply yarn should not let light through in plain areas. Loosely knitted cashmere on a coarse gauge is a cost-saving trick that produces a fluffy, insubstantial fabric.

Why Scottish and Italian cashmere feel different

Both countries buy fibre of similar grades, often from the same Mongolian sources. The difference is finishing. Scottish mills in Hawick and Elgin wash garments in the soft local water and raise the surface with dried teasel heads, which lift a gentle nap without breaking fibres; the result is full, downy and warm. Italian mills in Umbria and Biella prefer a lighter wash and a smoother surface, giving a sleeker, lighter, more fashion-oriented fabric. Neither is superior; Scottish cashmere suits a classic crew neck for a cold climate, Italian cashmere a fine cardigan for a mild one. Houses such as Johnstons of Elgin and Brunello Cucinelli represent the two schools at their best.

Why cheap cashmere pills

Pilling is mechanical: fibre ends work loose under friction, tangle with each other and form a ball that stays attached by a few fibres. Every factor that increases the number of loose ends increases pilling — short staple, single ply, low twist, loose knitting and, ironically, heavy milling in finishing, which makes a sweater feel soft in the shop by pulling fibre ends to the surface. A little pilling under the arms and where a bag strap rubs is normal even on Grade A cashmere and combs away; general pilling across the body within a few wears is a sign of short-fibre cashmere.

Reading a cashmere label

• "100% cashmere" is a legal claim in most markets, but it says nothing about grade. Look for micron or origin claims from the brand.
• "Grade A" or a stated micron (e.g. 15.5 µm) is a good sign, though unregulated. Brands such as Arch4 specify 13.5 µm baby cashmere; Loro Piana names its "Baby Cashmere" at around 13–13.5 µm.
• Ply is rarely on a label but often on a product page; 2-ply is the minimum for a sweater you expect to last.
• Country of manufacture tells you where it was knitted, not where the fibre came from. Both matter.
• Price is a signal: Grade A fibre, dehaired thoroughly and 2-ply spun, cannot be sold for the price of a cotton sweater.