U.K.-based global luxury fashion retailer Farfetch forecasts sales of $500 million this year, up from $300 million in 2014. In March the business -- which takes 30% of its orders from the U.S. -- closed an $86 million funding round, securing cash to boost global expansion.

Founded in 2008 by Portuguese entrepreneur José Neves, Farfetch provides online access to a network of more than 300 boutiques, with customers in 180 countries. Farfetch doesn't need its own inventory -- but it does need state-of-the-art technology to keep up with stock around the world.

Stephanie Horton is the CMO charged with creating a unique brand for Farfetch, differentiating it from rivals such as Net a Porter -- which recently agreed to a merger with Yoox and launched its own social media shopping portal, the Net Set -- and Vogue, which is set to launch its own global e-commerce site, Style.com.

With 90% of Farfetch purchases crossing borders, the search for something that your friends won't be wearing is a big motivation for customers. "People who come to our site tend to be looking for that slight edge," Ms. Horton said. "Even from our top 20 brands, which are probably similar to everyone else's, you are going to see a different selection on Farfetch, because a buyer in Tokyo is going to choose completely different pieces to a buyer in the U.S."

The "Unfollow" advertising campaign, developed with Droga5 Europe, positions Farfetch as a brand "for fashion lovers, not followers." In the print campaign, models are shown from the back. Ms. Horton explained, "We want to put the focus on the clothes rather than the person -- our customers are looking for things to help set them apart, not blend in."

The most recent campaign stars designer Vera Wang talking about how fashion enables people to express themselves, while previous videos have featured albino model Shaun Ross and Tokyo-based fashion power couple Verbal and Yoon.

In store, Farfetch branding is subtle. "We have no ambitions to become 'Farfetch the store'," Ms. Horton said. "The platform works because the boutiques are so individual, and they bring their own point-of-view to the site."

Most boutiques carry signs letting customers know they can shop the store 24 hours a day on Farfetch, and the Farfetch brand is also represented in a series of three $25 coffee-table books focusing on art, food and design, branded "Farfetch Curates."

An app, Farfetch Discover, continues the curation theme, capitalizing on the local knowledge of boutique owners by providing insider guides to many of the cities in its network.

Ms. Horton says her biggest challenge is scaling growth. "It's being able to keep the pace of growth and make sure that we are not sacrificing the quality of customer experience," she said.

In a bid to truly understand the customer experience, Farfetch recently bought iconic London boutique Browns for an undisclosed sum with the intention of creating a "store of the future."

"Obviously we want to make the shopping experience as fresh as it can be, but it's not about gimmicks -- you are not going to come in and see mirrors doing weird things," Ms. Horton said. "It's about technology making the customer experience the best it can be: same-day delivery, locating different sizes, a till-free checkout, click and collect."

Chicago-born Ms. Horton started her career in luxury as an account director at Draft Worldwide in Chicago, working on automotive brands Audi and Cadillac. From there, she moved to become marketing director at the New York Times, then to Vogue and on to Shopbop before moving to Farfetch as CMO two years ago.