Roman's dress, which has sparked the worldwide colour debate.
Does this £50 dress look white and gold or black and blue?
It is the question which caused arguments in offices around the world yesterday.
But now the question has been answered by the Birmingham-based firm which sells it.
Roman, which has its headquarters in Erdington and stores around the country, said it was categorically black and blue.
The colour became a hot talking point after a picture of the frock was posted online.
Some saw it as white and gold and others as blue and black.
The phenomenon began when Scottish singer Caitlin McNeill uploaded the image of the outfit to her blog after noticing her friends saw different colours in it.
She asked her followers: "Guys please help me - is this dress white and gold, or blue and black?
"Me and my friends can't agree and we are freaking out."
Some see the dress as white and gold.
The argument mushroomed and the image soon went viral as celebrities including Taylor Swift, Kim Kardashian and Justin Bieber joined the discussion.
The huge publicity was a massive windfall for Roman, based at Wingfoot Close in Erdington.
But fashion director Michele Bastock said she could settle the argument once and for all.
She said: "We never expected this.
"I went online when it all started happening and Facebook was going insane.
"I said: 'Somebody thinks it's white and gold’ so we brought it up on our website.
"I went and got the girls, we brought the dress up and it was definitely black and blue."
The reason why the two-tone fitted bandage dress is seen so differently has mystified many.
University of Birmingham psychology professor, Andrew Schofield, explained the natural phenomenon of "colour constancy" was the most likely cause of the confusion.
He said: "The physical colour of light coming from an object is made up of two components: the colour of the object and the colour of the light that shines upon it.
"The combined colour can vary widely.
"For example, daylight is much redder in the evening than at noon."
He added: "When the dress occupies most of the image, some people take the blue cloth as their reference for the illumination and thus see the dress as white cloth in blue light and the black frills as gold or yellow.
"Yellow things don't reflect much blue and so ought to look dark in a blue light.
"People correcting for a blue light will therefore see the dark frills as yellow.
"But other people may use the background objects as their white reference and thus see the dress as a blue garment in a yellowish-white light.
"These people will see the frills as dark because dark frills remain dark when compared with a white light."
The surge in demand for the dress saw Roman quickly run out of stock - prompting frantic negotiations with manufacturers.
More than a million visitors flocked to the company's website today.
The average day brings around 10,000.
Miss Bastock added: "We understood this was happening and so many big celebrities were talking about it but since 9.30am we haven’t stopped with media and customers.
"The stores are really, really busy."
The company now hopes to roll out a new white and gold version of the dress in the near future.