Returning to the stand in his family's civil fraud trial in New York, Donald Trump Jr described his father as "an artist with real estate".
The younger Mr Trump made the case for the Trump Organization that the ex-president was a "genius" with the ability to create luxury from nothing.
Prosecutors say the company inflated valuations to secure favourable loans.
A loss in court threatens the Trump real estate empire, which could be banned from doing business in New York.
Testifying on Monday morning, Mr Trump Jr continued the charm offensive seen in his first appearance two weeks ago, appearing relaxed, cheerful and confident.
Soon after being sworn in, he drew laughs by saying New York Attorney General Letitia James - the prosecutor bringing the case - might sue him for perjury if he said "it's good to be here".
And, nodding to his past complaints about the courtroom sketch art, he said he "already had a talk" with the artist depicting the day's proceedings and joked that he wanted the AI version of himself - with a strong jawline and broad shoulders - to be drawn.
He even made Judge Arthur Engoron laugh when he said: "I'm, like, the nongolfer of the family, which has relegated me to the children's table in perpetuity."
Dressed in a dark suit and light lavender tie, the Ivy League graduate spoke of going from bartending in Colorado to starting as a project manager at the Trump Organization, and then ultimately becoming an executive.
The company dealt with "world class assets" but was like a "mom and pop" business, he said, adding that it operated as a "meritocracy".
Defence lawyers put on a lengthy presentation to introduce evidence of "the Trump story" and recount the company's history.
When prosecutors objected that the lawyers were practically giving him a "script", Mr Trump Jr quipped: "Your honour, I promise I'll keep it under six weeks."
It was a light jab at the state, which took six weeks to present their case.
As lawyers flicked through various Trump properties, Mr Trump Jr expounded on each one, from 40 Wall Street to Seven Springs.
Trump Tower was the breakthrough project that launched his father's career and "the first time he changed the skyline".
"It would be one of the first great examples of ultra-luxury real estate emerging in Manhattan - the project by which all future high-end residential condominiums would have been judged," he said.
The Mar-a-Lago resort in West Palm Beach, Florida, was "one of the few sort of American castles", with a "virtually unheard of" location that placed it by the lake and also by the ocean.
"You couldn't build that atrium for $18m today," he said, challenging appraisers' assessments of the property's worth.
"You need to understand it and see it to actually fully grasp the spectacular nature of this property."
He described his father, who was not present in court, as someone who was on the leading edge of creating value in properties and could turn "eyesores" into "jewels".
"He see the things that other people don't see," Mr Trump Jr said. "He sees the thing that other people would never envision. He plays the long game."
Much of the testimony was largely unrelated to the claims at the heart of the case.
Judge Engoron has already ruled Mr Trump significantly inflated the value of his properties. The trial focuses on charges of falsification of business records, insurance fraud and conspiracy.
But the judge indicated he was willing to listen to how the defence's case plays out. The Trump lawyers have already floated filing for a mistrial, accusing the judge and his clerk of bias.
As prosecutors tried to object at various points that the presentation was irrelevant, he said: "There's no jury - I don't see any prejudice to this."
Later, after an objection to a document offered by defence lawyers, he asked prosecutors: "Do you want to risk a reversal over this one stupid document?"
The state had focused heavily on financial statements and spreadsheets, but Mr Trump Jr's encore set the tone for a defence case that may last into mid-December.
After two damaging weeks of testimony already from the Trump family, however, legal experts told the OceanNewsUK the case may be beyond salvaging at this point.
