Supporting her husband as he was sworn in as president, Melania Trump looked a vision in a baby blue custom Ralph Lauren dress and coat.

And as she stood by Donald Trump's side as he took the oath of office in the Jackie Kennedy-inspired ensemble, the designer saw their company stock soar.

When Ralph Lauren shares closed on Thursday before the inauguration, they were at $88.20 a share in what has been a quiet month for the American firm.

After Melania Trump stepped out in a baby blue custom Ralph Lauren ensemble for her husband's inauguration, the American fashion label saw a boost for their shares

A graph showing how Ralph Lauren shares peaked at $88.90 a share, an hour after Melania was first spotted wearing the outfit

However, by 11am yesterday, around an hour after Melania was first spotted wearing the designer's outfit, stocks spiked at $88.32.

By the end of trading yesterday, they had levelled off again, but still finished up at $88.90 a share.

Melania's double-faced cashmere creation consisted of a mock-turtleneck dress, over which she wore a short jacket with three-quarter length sleeves that featured a bold collar that clasped at the neck with a cutaway.

Melania's double-faced cashmere creation consisted of a mock-turtleneck dress, over which she wore a short jacket with three-quarter length sleeves

Melania's outfit saw it compared to that of the ensemble worn by Jackie Kennedy at the inauguration of her husband JFK

The outfit held well together throughout the day's festivities, which began with a coffee and tea ceremony with the Obamas at the White House.

But it wasn't just Melania who has been credited for Ralph Lauren's surge in the market.

Her husband's election rival Hillary Clinton also attended the swearing-in ceremony in an ivory Ralph Lauren pant suit.

However, it is not the first time that a designer has seen a upturn in business after a first lady has worn their creations.

Melania's husband's election rival Hillary Clinton also attended the swearing-in ceremony in an ivory Ralph Lauren pant suit

In 2009, Michelle Obama chose a Jason Wu gown, which gained the young designer a major boost in the fashion world.

While a Narcisso Rodriguez dress she wore for President Obama's State of the Union address in 2016, the garment sold out soon after.

But despite the so-called first lady effect, one designer has refused to dress Melania Trump.

Tom Ford says he will not allow her to wear any of his pieces despite the Wynn Hotel in Las Vegas erasing all traces of his products from its stores over the weekend.

In 2009, Michelle Obama chose a Jason Wu gown, which gained the young designer a major boost in the fashion world