NEW YORK - Once upon a time, a good investment piece was defined as a very versatile article of clothing that was expensive but worth it.

Take that Elie Tahari suit: At $500, worn 30 times over five years, you would pay about $16 per wearing. Wise purchase.

But that definition is shifting.

The best story coming from New York's Bryant Park tents - where more than 60 designers are showcasing their spring 2010 collections this week - is the latest incarnation of the fundamental wardrobe building block.

What once were pre-recession basics are now post-recession special.

"Up until recently, investment pieces were luxurious, but they basically revolved around the basics: the classic black pump, the little black dress, the must-have suit," said Sean General, the women's buyer at Boyds who has been traveling back and forth this week to see the collections.

"But for spring, we are seeing designers focus on items that are special - like Nima's [Taherzadeh] dresses and Yigal Azrouel's blouses that he layers. These items are being touted as investment pieces."

In this new post-recession fashion world, an investment piece is not just a good buy, but a piece that speaks to you emotionally. And from the looks of the spring 2010 collections - electric teals along with watercolor floral prints, one-shouldered gowns, tulip skirts, and body-skimming silhouettes - this is what designers are aiming for. In the process, they also are stepping out of their comfort zones, presenting fewer cohesive collections with a mix-and-match mentality, and more singular pieces that are distinct from one another.

Dress divas Tracy Reese and Nicole Miller took chances and sent funky ruched leggings down the runway. Diane von Furstenberg experimented with pants too, but she presented her roomier bottoms with layers. Alexander Wang took harem pants and gave them a football theme. (Maybe he was trading on the emotional nature of football, but this item just didn't move me.) Thakoon Panichgul, a favorite of first lady Michelle Obama, ran with the print dress.

In most cases, the details transformed the ordinary into the drop-dead fabulous.

Designer Lela Rose took a delicate pink sheath and added pleating detail to the bateau neckline for wow factor. English designers Justin Thornton and Thea Bregazzi bravely worked the tulip skirt in their Preen collection - some plain, some with tightly packed ruffle detailing. Devi Kroell added draping to over-the-knee skirts and dresses to appeal to our whimsical side.

Both Carolina Herrera and Tadashi Shoji worked basket-weave patterns into glamorous, jewel-toned gowns, and Karen Walker turned a raincoat into a must-have by cropping it and adding bell sleeves. (In a side note, Marc Jacobs, who usually is right on the money with his collections, didn't get the memo. His avant garde layering, ruffles, and Kabuki influence were disposable at best.)

In the Zero + Maria Cornejo collection - another Obama favorite - designer Maria Cornejo designated the Katy tunic as her investment piece.

Cornejo's men's and womenswear collection featured structured yet loose silhouettes in earth tones. "The ruching along the side is special."

The change in how we think about investment pieces follows other newly defined fashion code words. Luxury now has a lower price point, and doesn't require a label anymore. "It" items aren't defined by the number of celebrities wearing them, and the closet basics have gone from staid to sizzling.

Investment pieces always were meant for more than one occasion, said designer Pamela Rowland. "But [now] they want something they really love and haven't seen anywhere else." Among Rowland's spring 2010 collection presented yesterday is her investment piece: a silver, beaded tuxedo jacket.

Teri Agins was in Bergdorf Goodman a few weeks ago when she tried on a "fabulous" black dress by Roberto Cavalli. Price tag: $1,030.

The former Wall Street Journal fashion writer and current Vogue freelancer didn't want to spend that kind of money on a dress. But after she tried it on, the saleswoman told her the dress would haunt her.

She was right.

"I finally called her and gave her my credit card over the phone," Agins said. "I kept saying I'm never going to buy any more dresses. But that's the emotional boost I needed to go shopping now."

And that's what made the dress a perfect investment.

Contact fashion writer Elizabeth Wellington at 215-854-2704 or ewellington@phillynews.com.