LOS ANGELES -- The pocket square, that flourish of breast-pocket plumage that once belonged to the old school, has become a sartorial signature for a whole new generation of men, from the Hollywood celebrities and folk rock musicians who walk red carpets and grace magazine covers, to NFL players and the average guy on the street.

At a pre-Super Bowl press conference in New Orleans, it was Baltimore Ravens' linebacker Terrell Suggs' suit, tie and pocket square ensemble that earned honorable mention in press reports. During Hollywood's most recent awards-show season, it was guys like Taye Diggs, Eddie Redmayne and Justin Timberlake who made it hip to be pocket-squared. Then there's Bruce Willis sporting a jaunty number on the cover of the March issue of GQ magazine, and Mumford & Sons frontman Marcus Mumford wearing one on the cover of Rolling Stone.

So if it seems like pocket squares are popping up all over, it's not your imagination.

At Brooks Brothers, pocket square sales for 2012 were up 10 percent over 2011, according to Richard M. Cristodero, the chain's merchandise manager for men's furnishings.

Men's luxury e-commerce site Mr. Porter reports that the sales of pocket squares have doubled in the U.S. market. "And we foresee this continuing to grow," says Terry Betts, Mr. Porter's buying manager.

Even Chicago-based, mass furnishing e-tailer the Tie Bar saw a surge. "We sold twice as many pocket squares in 2012 as we did the year before," says Greg Shugar, co-founder and chief executive. "And we're seeing plenty of orders that are only pocket squares - where people are ordering five to 15 at a time and nothing else. For us, pocket squares used to be more of an add-on or impulse item, and now they're the main shopping purpose for some of our customers."

While it's clear that men (or those shopping for them) are buying more pocket squares these days, what they're buying requires that we delve a little deeper. Pocket squares, after all, encompass those crisply folded, razor-thin white badges of conformity (think "Mad Men") as well as vaudeville-magician-worthy acres of brightly colored silk.

For some, like Brooks Brothers or old-school independent Beverly Hills boutique Carroll & Co., it's the silk pocket square that still has the most traction. "We sell silks all year round," says Carroll & Co. President John Carroll, "(though) we do sell a lot of linen and cotton too."

It's those cotton and linen squares that are doing brisk business at the Tie Bar, Shugar says, and he has a theory why.

"I feel like it's the younger guys who are wearing the cotton ones," he says, "the ginghams, the madras, the white squares with the contrast piping at the edges. For them it's the final piece of their look."

Shugar's design team has used the renewed popularity of the pocket square to think outside the box, creating nontraditional versions out of wool suiting fabrics and nubby knit silk and, most recently, adding a fringed edge to a range of brightly colored gingham-patterned pieces.

Today's pocket squares aren't even necessarily square; menswear designer Alexander Olch, for example, offers "pocket rounds" - circular pieces of fabric that create an eye-catching floral feel when scrunched into a breast pocket.

Since it's the kind of fashion flourish often used to telegraph a man's attitude and individuality in situations where such opportunities are rare (John Carroll calls the pocket square the suit coat equivalent of the loud men's dress sock), it's not surprising that color has been king lately.

"There has also been a trend for color in recent seasons," says Mr. Porter's Terry Betts, "and we have seen a strong sell-through in cream and pink styles."

The solid-colored square with contrast-colored piping or edging was singled out by several of those surveyed.

"White (pocket squares) with colored piping are extremely popular," Shugar says. "They're probably our most popular. They've got that traditional feel but offer a small hint of color to modernize things and give the look a little bit of personality."

Which means this spring's most popular pocket plumage will definitely have a colorful edge to it.

• Read more articles by ADAM TSCHORN

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