In 1856, an 18-year-old named William Henry Perkin was home from London's Royal College of Chemistry for the Easter vacation, working from coal tar. What he made was mauve, the first commercialized synthetic dyestuff. Until then, purple had belonged to the Phoenician city of Tyre, where the dye came from the mucus of murex snails and twelve thousand of them gave barely enough to color the trim of one garment. Perkin turned the most guarded color in history into something a factory in Greenford Green could make by 1857. That is the quiet reason a purple sweater now feels ordinary to buy.

It is also why I think of purple as a color with a chip on its shoulder. It spent millennia as a status symbol and a few generations as a fashion fad, and this fall Vogue puts royal purple on the runways at Celine, Loewe, Mugler, Tory Burch and Balenciaga. The shades that matter for knitwear run from bright aubergine to jewel-toned amethyst, but I would start at the soft end.

The first group is all lilac and lavender, and it is the easiest way into the color. The Karen Kane crossover shawl collar sweater in lavender has a relaxed drop shoulder that I would wear over a white shirt with the collar out. The Hatley Emerson boucle in lilac is short-sleeved, so it works as a layer under a coat in October. For something quieter, the Kettlewell cable crew in chalk mauve and the LE BOP Palmer turtleneck in wisteria are the two I would pick for work, with gray trousers. The Chloe brushed alpaca polo in dreamy lavender is the fuzzy, dressy one.

My tip: hold a lilac knit next to your face in daylight before you commit. If it makes you look tired, go one step deeper, toward the wisteria or the lavender, and let the rest of the outfit stay neutral.

Plum is where purple stops reading as spring and starts reading as fall. A deep shade takes a coat, a scarf and a boot without any argument, which is why I would build this group around it. Vogue's fall color report calls the range bright aubergine to jewel-toned amethyst, and these eight sit in the middle of it.

The Kettlewell Maeve in blackcurrant is a rib-knit funnel neck with a relaxed fit, and I would wear it with straight jeans and flat boots. The Kettlewell Tina merino in dahlia is cleaner and more tailored, a good one under a blazer. The Universal Standard Flora v-neck in grape has a ribbed hem and cuffs that keep the shape, and the Show Me Your Mumu Emerson in merlot knit has a soft, textured surface that catches the light. The STAUD Sorrento in amethyst is a boxy short-sleeve cashmere, so I would layer it over a long-sleeve tee and treat it like a vest.

On color, Vogue says purple plays nicely with a red button-up and gray trousers. That works well with the Soft Goat Girlfriend turtleneck in bordeaux: add a red shirt collar and gray wool, and the whole thing hangs together. For brown, think leather shoes or a bag, not a brown sweater next to a purple one.

What I would skip: very dark plum in a thin knit if you wear a lot of black, because the two blur together at the neckline.

Cashmere is the fabric I would choose for purple, because a soft knit keeps the color from looking flat. Pull the sweater across your hand in the fitting room and watch the color shift: that is the test for whether the shade is rich or just loud.

The COS cashmere mock-neck in violet is the most saturated of the eight, with a clean modern shape, and I would wear it with black trousers and little else. The cashmere crewneck in orchid is a classic fit in a vivid orchid, the easy one for jeans. GOBI's essential Mongolian cashmere crew in dusted peri leans blue, which makes it a good match for navy and gray. The Tanya Taylor Adrien in blackberry is a turtleneck with a cap-sleeve shape, so I would wear it under a jacket. LISA YANG's Solene in soft lavender is sheer, so a camisole belongs underneath.

The two Pilcro pieces are a slouchy lavender turtleneck and an orchid henley with a buttoned placket, both 100% cashmere, and the Akris polo in malva is the polished one with a fine knit collar. Pair any of them with brown leather loafers and straight jeans. Vogue's tip for purple is to treat it as an accent or a grounding base, and that is exactly how a cashmere turtleneck behaves.

What I would skip: the sheer lavender on a cold day without a layer under it.

A cardigan is the lowest-pressure way to try purple, because you can open it, button it, or drape it over a white tee and call it done. The Caslon blend in purple tillandsia has a crewneck and button front, the sort of shape that moves from desk to dinner.

The Sanctuary cardigan in purple haze is relaxed and soft, and I would wear it over a gray dress. The Steve Madden Mica is cropped and fuzzy in dusty lavender, so it sits on top of high-rise jeans without bunching. The Splendid Bridget in orchid purple is a cotton v-neck with a pointelle-style knit, a good warm-weather option that still works in October with a long sleeve under. MAJORELLE's Jimella in lavender has short puff sleeves and pearl buttons, which is the one I would wear with a pleated skirt.

At the deeper end, the eberjey Recy crop in wildberry is a plum cropped v-neck, the SSKEIN Lesse in aubergine has a clean button front, and the Temperley London tonal T-logo cardigan in purple adds a small tonal detail. Check the buttons: they should sit flat and the placket should not ripple when the cardigan is closed.

What I would skip: a cropped cardigan with a cropped top underneath, since the proportions argue with each other.

Cable knits are a good test for a new color. A bold shade on a flat jersey can feel like a T-shirt; on a cable, it reads as a proper sweater, and purple suits that sculptural look.

The Hatley Dylan in lilac flecks and the Joe Browns chunky pullover in lilac are the two softest options, and I would wear either with dark denim and brown boots. Free People's Opal roll neck crop in purple satin is chunky and fuzzy, which I would pair with a long skirt. At the plum end, Guest in Residence's cable sculpted cardigan in fig and Polo Ralph Lauren's wool-cashmere cardigan in damson, with its small embroidered pony, feel like the grown-up versions, and either one wants a gray scarf. The 525 Alexandra in plum is a cotton cable with bow ties at the neckline, the Philipp Plein turtleneck in purple has puff sleeves, and the Jessica London crew in deep orchid is the plainest of the group.

Before buying, hold the knit up to a window: chunky cables show gaps if the yarn is thin. And if you are building an outfit, pair a purple cable with something smooth, like leather trousers or a satin skirt.

What I would skip: a chunky cable under a structured coat, where the sleeves bunch at the shoulder.

If I were buying one, I would pick by what I already own. Gray trousers and a red shirt point to plum. Brown boots and a camel coat point to lilac or lavender. A black wardrobe points to cashmere in a violet that is loud enough to stand up to it.

Purple went from snail mucus to a coal-tar flask to a knitwear rack in a little over a century and a half, and that is a lot of history to pull over your head on a Tuesday in October. I would keep the rest of the outfit quiet and let it have the stage. If you want to keep browsing, I also put together The Sweater Styles Worth Building A Wardrobe Around and Sweater And Knit Edit.