Cashmere
A luxury wool from cashmere goats — extremely soft, lightweight, and warm. Quality varies enormously; price is a rough proxy.
Cashmere is the undercoat of cashmere goats, harvested by combing during the spring molt. The fiber is finer than even ultra-fine merino — typically 14–19 microns — and produces yarns that are dramatically softer and warmer per gram than wool. A 14oz cashmere sweater is roughly twice as warm as a 14oz wool sweater of the same construction.
The quality range is enormous and the labels can lie. Grade-A cashmere from inner Mongolia (longer fibers, finer microns, hand-combed) holds shape, resists pilling, and lasts for decades. Grade-C cashmere from machine-shorn herds is barely better than wool and pills within a season. Most "cashmere" at retail under $200 is the latter.
The rough heuristics: a $400+ sweater from a brand that publishes the fiber length and origin is usually fine. A $79 cashmere sweater at a department store is usually thin, loosely-knit, and disappointing within months. The middle ground ($200–400) varies dramatically.
Care: hand wash cold or dry-clean. Never machine wash. Store flat or rolled — hangers stretch the shoulders. With proper care a good cashmere sweater can last 15+ years.
Merino wool
A fine-fiber wool from Merino sheep — softer, less itchy, and more breathable than standard wool. Used in everything from base layers to mid-weight knits.
GSM
Grams per square meter — the standard unit for fabric weight. Higher GSM = heavier, denser, often more durable.
Pilling
Small balls of tangled fibers that form on fabric surfaces from friction. Tells you about fiber quality, knit construction, and how the garment was made.