While they take different roles in the company, with Nicky being on the forefront of design and Simone the brains behind the business, the sisters agree that their success comes from mutual support and a shared point of view.
Here Nicky and Simone talk inspirations, mixing sisterhood with business and the casual beach-to-bar lifestyle in Sydney that inspires their line.
How did you get your start in swim design?
Nicky: I studied design in Sydney and I started Zimmermann as a ready-to-wear brand. Our swim comes from that point of view.
What is the biggest mistake you think women make when choosing a bikini?
Not taking enough styles to the fitting room. Sometimes it's the unexpected style that is the one that suits rather than the one you want to suit the most.
How does being from Australia, a place with a storied beach culture, affect your design process?
So much of what shapes Zimmermann is where we are from. There is so much of Sydney in what inspires me and in how I approach design and color and print. The casual beach to bar lifestyle is a big part of Sydney. I love the light in Sydney - it's just a city that glows.
Do you see a difference in how Australian and American women view swimwear?
Not so much with our customer. The woman from Bondi is looking to us for the same thing that a fashion conscious woman in New York or L.A. or London is looking for. They want something that resonates with their broader sense of style and that works with their wardrobe.
Is there a swim style you find universally flattering?
I love an underwire bra and a retro hipster style pant. It can suit so many woman and looks cool.
What is your favorite bikini you've ever worn and where did you wear it?
I'm strictly a one piece girl now but I loved our floral frill bandeau bikini that we did a few years back.
What is your favorite beach in the world?
Nicky: Tamarama, Sydney.
Simone: Whale Beach, Sydney.
What do you think is an iconic moment in bikini history?
Nicky: It was a one piece but I would say Bo Derek in "10."
The one piece - yay or nay?
What are your beach day essentials?
Invisible Zinc (sunscreen), bottled water, a wide-brim hat and a really big towel.
What is your ideal beach bag?
I love our handwoven raffia bags. They're big, bright and have these great colored pom-poms.
How would you describe the Zimmerman customer, the person you envision when designing?
She is passionate about special pieces, whether she lives in New York or Sydney. Zimmermann started out, and still is, inspired by the girl that's outside my front door in Tamarama.
How has being sisters affected your business?
Simone: It's always worked well because we have very different areas of responsibility. Nicky designs and I run the business. Sure we have had disagreements but on all the big things we always have the same point of view.
Nicky: I could never do what I do without Simone. She allows me the freedom to do what I want to do in the design room and that's a luxury. It's only ever been a positive thing.
Nicky is more on the creative side while Simone is more on the business side -- do you ever find yourselves switching roles?
Simone: I think I have a lot to offer creatively. Nicky doesn't necessarily agree....!
Nicky: I think I have a lot to offer with the business.....I'm only joking -- I like that I don't have to switch roles. That's the reason I think we do work well together because are roles are really clearly defined.
Would you tell one another if you didn't think a suit was particularly flattering?
Simone: Nicely, yes.