Black Caviar's unraced two-year-old half-sister now has a name - Belle Couture.

The filly had been known as "Pippa", after the sister of the Duchess of Cambridge, until a racing name was decided by her owners.

A daughter of Redoute's Choice out of Helsinge, the filly was purchased by BC3 Thoroughbreds for $2.6 million at the Australian Easter Yearling Sale in Sydney in April.

"Belle Couture is a filly with tremendous poise and strut, she is the princess of our stables," BC3's chief executive Bill Vlahos said.

"It's fitting to have a name that reflects such high-end beauty and style."

Belle Couture, who will be trained by Danny O'Brien, has started pre-training.