Jewelry designer Karen Karch says, “I like to work with organic shapes, then add a ‘bling’ factor.”

Despite the blinding “bling,” in the form of thousands of dollars worth of handmade jewelry that surrounds her, Ms. Karch, 40, is unpretentious. Her pieces and Push, her hip Mulberry Street boutique, have both been splashed across magazine spreads – but Ms. Karch would rather talk about her designs than boast about the celebrities who are wearing them.

When pressed to divulge their names, Ms. Karch – who has become a go-to source for uniquely modern yet organic wedding and engagement rings – hesitated.

“I think a lot of them have split from their partners, so I don’t think I should talk about them,” she said, though she will admit that she designed the ring Ethan Hawke gave wife Uma Thurman (speaking of the couples that have split).

Given the short-lived nature of many celebrity nuptials, Ms. Karch rejects every name she comes up with. Finally, she settles on Marissa Tomei. “She didn’t come to me for a wedding ring,” Ms. Karch said.

Did she design her own wedding band? “Originally, no. I knew that if I designed my own ring I would always want to redesign it, and I wanted something that could be permanent,” Ms. Karch said. Now that she runs her own store, she changes wedding bands regularly, using her ring finger to showcase her latest designs.

Many customers are in the market for something other than a band of gold (or silver or platinum). Ms. Karch’s designs are at once funky and elegant – lending even the rarest specimens a laid-back appeal that allows the wearer to pair precious gems with a T-shirt and jeans. Her pieces are virtually staples in Lucky magazine; the cover of Lucky’s August issue features model Molly Sims sporting a pair of diamond earrings from Push.

One of her signature pieces, the tiara ring, features a series of jewels arranged in a crown-shaped pattern. A popular necklace bears a stone in a horn shape. Ms. Karch described her designs as “wearable and pretty, but with an edge to them.” Prices range from $200 to $30,000.

Ms. Karch first enrolled in a jewelry-making class during her last semester at the University of Texas at Austin. She loved it, and went on to hone her skills at the Parsons School of Design. Post-Parsons, Ms. Karch moved to L.A., supporting herself as a waitress while designing jewelry out of her apartment to sell to small shops. A jewelry-store owner soon hooked her up with a wholesale sales representative.

“Before I knew it, I was in the [wholesaler’s] showroom. If I’d had my choice, I would have said, ‘I’m not ready,’ but I said, ‘Okay, I’ll do it,'” Ms. Karch recalled. About six months later, with her items being sold to increasing numbers of stores, she was able to stop pushing plates and devote herself to her craft full-time.

Ms. Karch met her husband, Frank Ford, while living in L.A., but the two soon moved to New York, settling in Nolita. A vacant storefront in the couple’s new neighborhood inspired Ms. Karch to act. She had been moving away from delicate, feminine pieces, and other store owners often shied away from her increasingly bold and edgy designs.

“I knew the only way I could see if [the new styles] were going to work was to sell them in my own space,” Ms. Karch said. “The rent was low – the neighborhood was not really developed at the time – and I figured if the store didn’t work out I could always just use it as my workshop.”

Ms. Karch and Mr. Ford rolled up their sleeves and designed the space together, and Push opened its doors in 1996. Despite the couple’s lack of interior-design experience, the resulting space is sophisticated and unpretentious.

Simple wooden display cabinets, with gold dragon pulls cast by Ms. Karch herself, line the walls. The jewelry displays, much like the pieces themselves, exude playful irreverence. An old radio holds shiny bracelets and necklaces, and rings share a cabinet with New York souvenir snow globes. “One thing I think is important about my jewelry is that it looks like a per son made it, and I wanted the store to have the same feeling,” Ms. Karch said.

Three years after Push opened, Ms. Karch’s husband decided to follow his dream of opening a restaurant. Eight Mile Creek, which serves fare from Mr. Ford’s native Australia, opened in a choice location – right next door to Push. The two shops nestle in the shade of matching blue awnings and Ms. Karch said, “we’re good business partners.”

In mid-September, Ms. Karch is launching Push’s first men’s line. The collection will include cuff links, rings, bracelets, and money clips. She also wants to open another store, and is looking at uptown locations, including some on Madison Avenue. She dreams of expanding across the country and even around the world – Las Vegas, New Mexico, London. She was approached to teach a class at NYU, and would like to do so if she could only find the time.

Ms. Karch explained the philosophy behind her store’s name: “Push implies moving forward. It’s about pushing the boundaries a little bit. It’s somewhat aggressive.”