Vendors and hole-in-the-wall shopkeepers will beckon you in to look at their wares: "One of a kind", they proudly proclaim. Baby alpaca, hand woven by my grandmother on her deathbed.
Price should be the first giveaway. A real baby-alpaca sweater would sell for more than s/200. So maintain your skepticism even if the label boldly states 100% BABY ALPACA. False labels are common on acrylic-blend clothing throughout the Cusco area.
A good-quality label should show the maker's or seller's name and address. You're more likely to find quality goods at an upscale shop, of which there are several around town.
Such a business is just not going to gamble its reputation on inferior products.
Texture is the classic piece of evidence. Baby-alpaca products use hairs, 16-18 microns in diameter, taken from the animal's first clipping. Subsequent shearings from a more mature alpaca yield hairs with a 20-micron diameter, still quite soft, but never matching the legendary tenderness of baby alpaca (for that reason, women tend toward baby-alpaca products; men navigate toward regular alpaca). A blend with llama or sheep's wool is slightly rougher to the touch and, for some people, itchier to the skin. And if the garment is too silky, it's likely a synthetic blend (the occasional 100% polyester product is passed off as alpaca to unsuspecting buyers.)
While "one of a kind" denotes uniqueness-and, again, be aware that much of what is claimed to be handmade here really comes from a factory the experts say there is nothing wrong with factory-made alpaca products. A garment really woven by someone's grandmother lacks a certain degree of quality control, and you may find later that the dyes run or the seams come undone.