Donald Trump lied about the $1million discount he received for a 10-carat Graff Diamonds engagement ring bought for Melania in 2005, reports state.

Graff Diamonds' chairman, Laurence Graff, claims Trump's admission to the New York Times was a lie.

Graff asserted - in an email sent from his home in Gstaad, Switzerland, on January 26 - that while it was 'a pleasure to do business with' Trump, he was given 'no favours' when he bought the D-flawless cut 10-carat diamond.

Graff Diamonds' chairman, Laurence Graff (right), revealed that Trump's admission to the New York Times in 2005 that he got a $1million discount was a lie

Graff asserted - in an email dated January 26 from his home in Gstaad, Switzerland - that while it was 'a pleasure to do business with' Trump, he was given 'no favours' when he bought the D-flawless cut 10-carat diamond for his engagement to Melania in 2005

The London-based company was said to have received increased publicity as a result of the discount Trump received, the Times reported.

'Only a fool would say, "No thank you, I want to pay a million dollars more for a diamond,''' proudly boasted Trump in the 2005 interview.

'We don't sell items for publicity value,' explained Graff CFO Nicholas Paine to Forbes.

A third source familiar with the transaction said that Trump was lying about the purchase and that he paid in full

'Only a fool would say, "No thank you, I want to pay a million dollars more for a diamond,''' proudly boasted Trump in the 2005 interview with the New York Times

While Graff and Paine refused to disclose a price to Forbes, the Times had reported that the ring was retailed for $1.5million.

'He paid for [the ring] in full, and he paid immediately,' said a third source, with direct knowledge of the transaction, to Forbes. They further asserted that Trump did indeed lie about the deal.

Trump purchased - in full - a second Graff diamond for Melania in celebration of their 10 year anniversary in 2015.

Melania famously posed with the large 25-carat ring for her official White House photos.

It is reported to be worth $3million.

Trump purchased - in full - a second Graff diamond for Melania in celebration of their 10 year anniversary in 2015