LOS ANGELES — Many contemporary art collectors have an adviser. Arthur Lewis is lucky enough to have a mentor, instead. A decade ago, Mr. Lewis, then a merchandising executive at the Gap, and his partner, Hau Nguyen, who owns hair salons, invited the collector Joy Simmons to their home here, where they had art by popular provocateurs like Jeff Koons and Paul McCarthy.

She was not impressed. “Joy told us we have to take everything off our walls and start all over again,” Mr. Lewis said. “She said we have an opportunity to make some impact by collecting artists who are not getting their moment to shine, artists in our own community.”

“I’m really grateful for what she said,” he added. “It helped us discover our passion as collectors: artists who tell stories that we understand personally as two people of color.”

Now, they own a range of work by emerging black artists and those already in demand, like Amy Sherald (who painted Michelle Obama’s portrait in 2018) and Kerry James Marshall (whose work set an auction record that year for living black artists). There’s also a strong Los Angeles contingent, including Lauren Halsey, Genevieve Gaignard and Diedrick Brackens.

In 2012 the couple renovated their Italianate home to create more space, and more walls, for art. Last year, Mr. Lewis turned his avocation into a vocation, taking a job at United Talent Agency, overseeing the division representing visual artists in entertainment and licensing deals. This team also runs an unconventional gallery, UTA Artist Space. It has a show of fiery figurative paintings by Arcmanoro Niles opening Feb. 12, in time for Frieze Los Angeles. These are edited excerpts from a conversation with Mr. Lewis.