Towards the end of the first season, Victoria has an affair with an old flame, an artist named Dominik Wright. Dominik and Victoria have a dark secret: before Victoria's marriage to Conrad she worked with Dominik selling fake paintings to the wealthy. Victoria later abandoned Dominik for the wealth and prestige that Conrad offered, but as her marriage fails she turns to him once more. Towards the end, they have this little affair, which results in nothing as Conrad eventually drives Dominik away. But no matter: we're left with a gorgeous painting of Victoria.
In the show the painting is a labor of love, and it's certainly very easy to love. Even if as an Expressionist piece, it's a little muddled... there's nothing that can be done. As an aside, I believe the "real life" artist is an Expressionist artist named Chris Hero. His name appears on IMDB under "original artwork," so I'll assume that it's him. If it's not, and you know who it is, let me know!