Cashmere Grades A, B, C: What the Micron Number Actually Buys You
Two numbers, three grades
Cashmere is graded A through C, and the grade is two measurements. Grade A is the thinnest, longest, and most durable: fibres about 14 microns across and around 36 millimetres long. Grade B runs about 19 microns, thicker and longer on average than A, and still makes high-quality cashmere. Grade C is the lowest quality: fibres about 30 microns across, short, thick, and cheap. For comparison, a human hair runs 70 to 100 microns, so even Grade C cashmere is fine. It is fine in the wrong direction.
The numbers matter because of how yarn works. When fibres are spun together, they interlock, and long, thin fibres form a stronger bond than short, thick ones. A little friction pulls a low-grade garment apart more easily than a high-quality piece, because the short fibres work loose and tangle into pills. The International Wool Textile Organisation puts it plainly: longer fibres resist migration and breakage, which is what pilling is. Fibres under 25 millimetres break and pill far more than fibres over 30 millimetres, and the best pieces run 36 to 40 millimetres.
Why the grade is not on the label
Nothing on a swing tag tells you the grade. The label says 100 percent cashmere, and 100 percent cashmere can be Grade A or Grade C, and the price is the only hint, and a weak one, because low-quality cashmere can still make expensive products. The tests that work are the ones you can do in the shop. Rub a layer between your fingers: low-quality cashmere pills immediately. Hold it to the light: a loosely knit, low-gauge piece has more loose fibres to rub together, while a tightly knit 12 to 14 gauge piece resists it. Ask about ply: a 2-ply yarn, two strands twisted together, holds up better than a single-ply shortcut.
That is also why pilling has causes you can fix and causes you cannot. A Grade A sweater pills a little at first, from surface shedding, and then settles. A Grade C sweater pills structurally, from short fibres working loose, and no comb fixes the fibre. The comb removes the pills. It does not change the grade.
What to buy, and what to skip
Buy the longest, finest fibre you can afford, and buy it in a tight knit. A Grade A piece at 14 to 16 microns and 36 millimetres or longer is the combination that resists pilling, and the 2-ply construction is the second thing to check. The price will be higher, and the price is the point: the fibre is the cost, and a cheap cashmere sweater is cheap because the fibre is short.
Skip the piece you cannot test. If the shop will not let you feel the knit, or the brand will not say anything about fibre length, the grade is probably not the selling point. Merino pills for the same reason, short fibres working loose under friction, and the fix is the same: longer fibre, tighter knit, and a day of rest between wears. The grade is not a luxury detail. It is the difference between a sweater that lasts five winters and one that pills in five wears.
Frequently asked questions
What are the grades of cashmere?
Cashmere is graded A through C. Grade A is about 14 microns across and 36 millimetres long. Grade B is about 19 microns. Grade C is about 30 microns, short and thick, and the cheapest.
Why does cashmere pill?
Pilling happens when loose surface fibres rub together and tangle into small balls. Short fibres under 25 millimetres break and pill far more than long fibres over 30 millimetres, and loose knits pill more than tight ones.
How can I tell cashmere quality in a shop?
Rub a layer between your fingers: low-quality cashmere pills immediately. Check the knit density, tightly knit 12 to 14 gauge resists pilling, and ask about ply: 2-ply yarn holds up better than single-ply.
Is expensive cashmere always better?
Not always. Low-quality cashmere can still make expensive products. The grade comes from fibre diameter and length, not price, so test the knit and ask about fibre length before you trust the tag.