Is it the A-line dress or the little black dress? The stiletto or the kitten heel? The cashmere sweater or the denim jacket?
One of fashion's leading authorities is set to reveal the answer to the question women keep on asking her: what are those timeless pieces, guaranteed to survive all the fads?
What are those 'must-have' items that, when trends die away, a woman can turn to with confidence?
One Hundred, A Guide To The Stylish Pieces Every Woman Must Own, contains the Holy Grail: an exhaustive list of the essential must-have pillars of the fashion world, culled from the notebook of one of the industry's most stylish women.
Nina Garcia is a fashion authority par excellence. She is author of the wildly popular The Little Black Book of Style, now in its eighth reprint since its publication less than 12 months ago, fashion director and editor-at-large of Elle magazine and soon to be fashion director of Marie Claire (Editor's note: not our Marie-Claire). She will also be a judge on the Sky TV show, Project Runway.
"In my years as a fashion director, I watched many fads come and go but also observed how certain items are always part of the rotation," she said.
"Some may sit out for a year or two, but always come back. The colour may change, the fabric may change, the designer or brand might change, but in essence the items in my book have always been the backbone of fashion and, with a bit of sub-editing, each has been one of my touchstones."
The list is comprehensive.
From Aviator sunglasses to crisp white shirts to opaque tights and zippered hoodies. But Garcia has her favourites: "If they haven't already, women must do two things. Splurge on a pair of shoes. It is one of those things you can't fake. You can't look well dressed without a nice pair of shoes, it is impossible. And get a dangerously sexy, little black dress. It is immaterial if it's Balenciaga, Alaia, Topshop or H&M. If you don't have one, now is the time to find it."
But, no matter how small or apparently insignificant, every woman must, according to Garcia, have a red lipstick, an old concert T-shirt and a push-up bra.
She explained: "These pieces have been with me season after season. They have been with me through thick and thin. Simply put, these items make me feel classic. And there is no substitute for feeling this way. Ever."
The idea for the book came to Garcia when she had to move out of her flat for two years. "Every once in a while, I'd run back to the apartment to snatch an item or two," she said. "Over the months, I must have run back about a hundred times. And soon I realised I had the answer to the questions that women kept asking me: 'What are the essentials? What are the 'must-haves'? They are the items I ran back to my apartment for, the items I simply cannot imagine living without.
"We're all fashion chameleons. We all wake in the morning and sometimes we feel like we want to be more classic, or more edgy. The book addresses all of those different moods."
But, just as in every good fairytale, the gold at the end of the rainbow comes with conditions _- and severe warnings. "Self-editing is key," said Garcia. "The list is a only a guide, a barometer of items that have withstood time and seasons, fads and trends. Any woman who does not alter the items on the list to suit their personal style is not playing the style game correctly.
"It would go against the very nature of fashion and style and the frenetic rebelliousness inherent in a truly stylish woman who walks down the street wearing that perfectly unexpected mix of colour and fabric. Style is dangerously unpredictable."
Rather than being a rule book, what Garcia hopes she has written is a framework every woman can 'think and ponder'. "Style is a deeply personal expression of who you are, and every time you dress, you are asserting a part of yourself," she says.
Fashion cycles are becoming shorter and frighteningly fast. Although the pressure to keep up with trends and make the correct choices is intense, Garcia advises women to calm down.
"Don't be moved by these fashion distractions," she said. "Don't be the woman who gets caught up in the fads. You should be the woman who has a personal style and is not afraid to wear your favourite 100 pieces repeatedly.
"Repetition is a sign of style. Women who wear a new outfit every single day are fashion victims. When you change your look so many times, it seems like you are confused. Yet, when you invest deeply in pieces that you love and will love, season after season, these items become yours. They show the world that you know who you are. You are no fashion victim. You are an original."
Susan Wagner, a fashion journalist and author of Cigarette Country, has called the list 'provocative and inspiring'.
It is, she said, "like a timeless issue of Vogue, one that is beyond trends. The joy of Garcia's approach is that she is not urging you to rush out and shop, but instead to look carefully at what you own and how it works, and to think about how you can add classic, timeless pieces to your closet to build a stylish, functional wardrobe."
Must-haves for the wardrobe
l The A-line dress
A 'just in case' dress. As in, 'just in case' you are invited out on an impromptu date and only have five minutes to get ready.
l The ballet flat
Although it will never have the transformative power of the high heel, a ballet flat is chic and timeless.
l Denim jacket
Buy it a size too small or find a really fitted model. Do not wear with another piece of blue denim.
l Fishnets
Teasing with fishnets is incredibly sexy and intriguing.
l Man's hat
Fedora, Trilby or Panama. There are few things sexier than a woman who just threw one on and walked out to greet the world.
l Havaianas
Pronounced ah-vai-YAH-nas (flip-flops to some) the so-called 'democratic sandal' is a national treasure.
l IPod
What started out as a utilitarian device is now an essential fashion item.
l Jeans
Ignore denim snobbism. Pick a jean that fits you perfectly and stick to it.
l Knee boots
As skirts get shorter, boots get higher. Useful for making men go weak at the knees.
l Nail polish
Vamp red or black satin. Corals and fuchsias are just asking for trouble.
l Old concert T-shirt
Few things are cooler than an overworn shirt from a concert by the Stones, the Strokes, Led Zep etc.
l Pencil skirt
Immediately conjures up images of femmes fatales.
l Red lipstick
Nothing says Hollywood glamour like a red lip.
l Stilettos
This shoe is capable of invoking euphoria, admiration and panic. A woman wearing the right stiletto is a true force to be reckoned with.
l Tuxedo jacket
Androgyny is forever chic and avant-garde. It should hang like a man's tux but be slender.
l Wrap dress
If a dress was ever designed to flatter a woman's figure, this is it.