In 2012 Christian Louboutin introduced the Kate, a pump named for Kate Moss, and in 2013 he followed it with the So Kate. Harper's Bazaar describes the difference plainly: the So is "spindlier and slimmer, cut lower on the vamp and with a higher heel." It reaches 120mm, and the sides are cut away so the foot shows. I think of it as a drawing of a shoe, and that is why people keep wanting one in their own closet.

The brand's own line explains the appeal. Louboutin says the style is simple and complex at once, and that if the line is not perfect, there is no embellishment to hide it. That is the whole lesson for anyone shopping around it. A Louboutin So Kate dupe, in the sense I mean, is not the original and does not pretend to be. It is a pump from another label that shares the detail that sells the shape: a sharp point, a thin heel, a low-cut vamp. The red sole is the brand's protected trademark, so nothing here has one.

Start with the pointed pumps. The Steve Madden Hexx is black leather on a thin stiletto with a seam running up the toe, a sharp take on the low-cut vamp. The Schutz Miranda is the closest read of the original in this group, with a long slender point in glossy black patent. I like the Sam Edelman Hazel for its tan lining, a small surprise when you step out of the shoe. The MICHAEL Michael Kors Alina Flex in black leather is softer, and the Steve Madden Allude in light brown suede is my pick for an October skirt with dark tights.

Put your hands on the vamp before anything else. The line should dip low and stay clean, with no extra seams cutting across it. Then look at the heel from behind: it should drop straight, not lean.

Patent is where a pump's shape gets tested, because gloss shows every wobble in a line. Vogue calls a classic black pump as wearable as your go-to LBD, and the finish only sharpens that. In my fashion dreams she is leaving a late dinner in a camel coat and a pair of these, the heel clicking on wet pavement.

The Stuart Weitzman Vinnie 85 is the one I would study first: high-shine patent with a flared slim heel, leather lining and a leather sole. The Sam Edelman Hazel in black shiny patent and the Steve Madden Dynasty both keep the thin stiletto and sharp toe that make the original's silhouette. The Kurt Geiger London Regent adds a gold metal toe cap, a detail I like when the black needs a bit of company. Schutz Ophelia has a scalloped topline, which is a different idea, so I would pick it for a softer mood. The Nine West Graysin is a faux patent with an ankle strap, and the Tony Bianco Asti is a slingback, so both change the line a little.

Test the gloss in daylight. Run your eye along the toe: patent should read as one smooth sheet with no ripples near the point. Check the heel cap and the stitching at the back, since that is where rough finishing tends to show.

What I would skip: a patent pump with a chunky ankle strap if you are after the low, open vamp. The strap shortens the line you came for.

Kate Moss gave the Kate its name, and a nude pump suits the idea: skin-toned shoes disappear into the leg and let the point and heel do the talking. The brand's own page says the Kate comes in patent, suede and calfskin, so tone and texture are a choice, not a rule.

Schutz Lou in light nude is leather with a slender stiletto and a leather sole, and it is the one I would reach for first. The Steve Madden Dynasty in blush patent has the thin 4.25 inch heel and a little shine. ALDO Lala in beige suede is soft and matte, which is good with wool trousers in October. Kate Spade New York Daphne in pale vellum has a quiet, creamy tone, and the Sam Edelman Vienna in French Sand carries the low-cut vamp in a sand leather. The Naturalizer Anna is nude leather on a slim high heel, the Bruno Magli Tara sits in sand with a slender heel, and the Pelle Moda Aeri trades height for a kitten heel.

Hold each pair against your skin in daylight, because nude is a sliding scale. A pump a shade lighter than you looks bright; a shade darker looks like a boot. Take a photo and check that the heel and the toe line up with your leg.

What I would skip: a nude with a visibly plastic sheen on the toe. If it looks plastic, the point loses its drama.

A slingback keeps the pointed toe and thin heel but swaps the closed back for a strap, which makes the foot look longer and the heel look thinner. Harper's mentions a So Kate 70 leather slingback among the versions people keep coming back to, so the idea has some history. It is a neat way to wear the shape for a long dinner or a wedding in November.

Schutz makes two I would put side by side: the Liora in sugar white, a leather slingback with a thin 4-inch heel, and the Alessia in black patent, a slingback with a slim strap round the back and a thin stiletto heel. The Sam Edelman Tegan in French burgundy is the one I would wear with a black coat and dark tights. Arezzo Bowie in black and Kenny in cocoa both give a calm, leathery take, and Nine West Gerts in natural suede is the softest. The Calvin Klein Biancya is black leather and plain in a good way, and the Mango Mica in brown is the lightest touch of the group.

Check the strap before you trust the shoe: it should sit snug at the back of the heel and not slip off when you walk. Look at where the strap meets the heel, since that is where a slingback fails first. Then check the vamp line, which should stay low and clean even with the strap added.

What I would skip: a slingback with a very wide strap or a thick buckle. It breaks the thin line that makes the shape read.

Louboutin's own line is that without trim there is nowhere to hide, so I think embellishment is the place to be careful. Trim should sit on the vamp or strap and leave the point and heel alone. In my fashion dreams she walks into a December party in midnight satin, a single crystal brooch catching the light.

That is the Badgley Mischka Cher: midnight satin, a crystal brooch on the vamp and a leather sole. Its sister, the Rania, is white floral lace on a slim high heel and sits well with a slip dress. The Betsey Johnson Brice is covered in rhinestone florals and is a bold choice. Anne Klein Itzy is crystal-covered in a slingback, the Nina Billie is black satin with a crystal strap, and the Kurt Geiger London Zip Court is crystal-studded and slim. The Bella Vita Azalea in silver satin has stone and crystal trim, and the Ron White Haisley in champagne ombre crystal is the glitter pick of the group.

Tilt each pair under a lamp. Stones should be set firmly with no gaps showing glue, and the satin should lie flat with no puckers at the toe. Run a finger along the edge of the sole where trim ends.

What I would skip: crystal across the whole shoe if you wear it more than once a season. One focal point, such as a brooch or a strap, goes further with a coat and a dark dress.

I would begin with what I will wear most: black leather with a low vamp and a thin heel, then a nude for the days that call for lighter. Check the vamp line, the heel from behind and the strap, in that order.

If a pair has a clean point and a slim stiletto, it shares the original's idea. Wear it with a good coat and a plain black dress.

Louboutin once said the line has to be right because there is no trim to hide behind. I would take that as the test for every pair here.