Timeless Treasures : Clothes that have remained in wardrobes for years can look as current as when they came off the racks. Such classics should be the building blocks of every wardrobe.

Fashion trends come and go, but classics like a boxy Chanel jacket, St. John knit or navy Brooks Brothers suit never die.

Clothes that have remained in wardrobes for years can look as current as when they came off the racks. There are people who proudly sport 10-year-old jackets, 20-year-old cashmere sweaters and 30-year-old Levi’s--and nobody is the wiser.

Fashion consultants say such classics should be the building blocks of every wardrobe. The key is knowing which styles are timeless and which will go the way of yesterday’s bell-bottoms or today’s vinyl miniskirts.

If a garment has limited use, if it can’t be worn to a variety of places and doesn’t mix well with other pieces in the wardrobe, then it’s probably not a classic, says Kitty Leslie, a Laguna Niguel fashion consultant. Wearability is the key to determining a style’s longevity.

“If it’s for a rock concert, it’s not a classic,” Leslie says. “A perfect example of a classic garment is a blazer. It’s wearable. It can be worn on many occasions. It also adapts to many pieces of the wardrobe.”

Styles become classic because they look good on most people.

“Combat boots don’t look good on everybody, whereas a tennis shoe or an espadrille does,” she says.

Blue jeans and trench coats are other examples of classics. Stirrup pants started out as a trend, but women like the way they look in them so much that they’re on their way to classic status.

“A stirrup pant gives a good, flattering line and will take a jacket, blouse or a sweater, whereas a wide-legged pant only takes a certain style of jacket,” Leslie says.

Knit dresses by St. John have become classics that women wear for years. Marie Gray, designer and co-founder of St. John in Irvine, says the garments’ simplicity makes them timeless.

“Many things that are timeless are simple pieces that are easy to wear. They’re not on the cutting edge of fashion, but they’re always elegant,” Gray says.

St. John uses a timeless material--wool knit--and classic ornamentation such as buttons and belt buckles that look like jewelry for long-lasting looks.

“You can’t really tell what season they were created,” Gray says.

Customers have sent St. John pieces that are 10 or 20 years old to the company for alterations. One recent arrival, a pale yellow sheath with crocheted detailing, was made just a few years after St. John began in 1962 but does not look out of date with today’s lacy, feminine styles. Women hold onto these dresses because they’re highly wearable, Gray says.

“I design with the idea that these have to be worn by real people to real places. It’s not for flash on the runway. It’s for luncheons, the office, a great dinner party,” she says. “You can dress it up or down and take it from day to evening.”

To be truly timeless, a garment has to be versatile, says Sandy Deem, district manager of Episode, a women’s clothing store in South Coast Plaza, Costa Mesa. A one-button, hip-length jacket can be worn years because of its versatility.

“You might see it with slightly larger or smaller shoulder pads, but it’s always in style,” she says. “Then you can accessorize it.”

Pairing a classic with something trendy like fall’s cropped mohair sweaters keeps them looking fresh, she says.

Other classics on her list are cashmere turtlenecks and cardigans and trousers with pleated fronts.

“I’ve had a cashmere turtleneck for six or seven years. You wouldn’t know if I bought it yesterday,” she says. Ditto for her wool gabardine, double-breasted jacket.

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For men, styles have changed dramatically in the past five years, yet it’s still possible to avoid clothes with short life spans, according to Bjorn Sedleniek, owner of POSH, a men’s clothing store in Fashion Island Newport Beach.

Fashion-forward clothing such as Armani suits have exaggerated features, including extra-wide shoulders, drapey silhouettes and lapels with low notches.

“It breaks away from the conventional look of a tailored coat,” Sedleniek says. “What keeps a suit classic is the notch of the lapel, the lapel width and how it tapers through the waist.”

Suits that fit the body well and have a natural shoulder are more likely to last from season to season.

“Classic suits have a tendency to truly fit, which makes them more comfortable to wear throughout the day,” Sedleniek says. “Trendy, oversize suits may look great, but often they’re not as comfortable. . . . If the shoulder doesn’t fit, by the end of the day it will be dragging you down.”

A solid navy, navy pin-stripe or dark gray suit that fits well will never go out of style, he says.

“No matter what fashion wants to do, they’re not going to do away with good, classic clothing,” Sedleniek says. “You can still put on the same navy blue suit you bought five years ago and not look dated.”

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For clothing to be classic, it must be made of classic material. Linen, wool and knits are timeless because they’re wearable, Leslie says.

“What isn’t classic are the transparent fabrics,” she says.

Crinkled rayon skirts and dresses, while flattering on many figures, appear destined for extinction because their wrinkles makes them difficult to mix and match with other pieces in the wardrobe, she says.

The material’s print and color can also date a garment. Leslie steers away from prints because they’re harder to match with other pieces than solids. For someone who wants to wear prints, she recommends more timeless and versatile polka dots and stripes.

Classic colors such as navy, black, red and white help prevent a garment from aging.

“Those are forever. It’s when you get into hot pinks and other brights that you may not be as fond of (a garment) next season,” Gray says.

Trendy earth tones such as olive and brown that have been strong in menswear for the past five years are likely to die out, says Orvey Hampton, manager of Tom James of Orange County in Irvine, a men’s clothier that travels to the client’s home or office.

“They come and go because people get tired of them. But navy, charcoal and blue-gray are timeless,” Hampton says. “Men will wear those long after we’re gone.”