Rembrandt van Rijn, Self-Portrait, 1659, National Gallery of Art, Andrew W. Mellon Collection. Rembrandt. We know the name, but do we know the work? A new exhibition is at the North Carolina Museum of Art in Raleigh. "Rembrandt in America" highlights both authentic and inauthentic Rembrandt paintings - side by side. Fred Wasser has this story of the artist and those who copied him. If you lived in Holland in the mid-1600s - and wanted a portrait of yourself, and had the money -- Rembrandt was the go-to person. Museum curator Dennis Weller. "Before Rembrandt, portraits in the Dutch Republic tended to show individuals - certainly the features were there - but they were rather stiff and static," says museum curator Dennis Weller. "You didn't think that they breathed air and they had blood running through their veins. When you get to Rembrandt you'll see that he brings those elements into his paintings. He's able to very wonderfully and effectively capture the personality of the sitter in a way that previous portrait painters just were not able to do." The way he paints the musculature about the eyes. The way he controls the light. The emotion in the face. The soul - somehow -- revealed. It was once thought that Rembrandt produced a total of about 700 works. Today we know that the number of authentic Rembrandts is probably less than half of that - about 320. "All the clues could say it's a Rembrandt, but it doesn't look like a Rembrandt. Probably isn't," says Noelle Ocon, the North Carolina Museum of Art's conservator of paintings. The confusion about Rembrandt comes, in part, because Rembrandt taught his workshop assistants and students to paint in his style. According to Guild rules of the time, if one of his pupils did a painting in his workshop, Rembrandt could sign it. The master had imitators also. And there were scoundrels who passed off their work as Rembrandts. So, how do you tell the difference? Rembrandt or not Rembrandt? X-rays, infrared photography, chemical analysis - they go only so far, says conservator Noelle Ocon. I can't imagine the technology of something that'll definitely say somethings a Rembrandt." She says the eye is still the most important instrument. Yet we know the eye is famously fallible. In the 1950s, the North Carolina Museum of Art's director - reknowned Rembrandt scholar William Valentiner - recommended the acquisition of two Rembrandts for the museum. They were displayed when the museum opened in 1956. Years later, it was discovered that those paintings were not Rembrandts. One is now attributed to Rembrandt's colleague - painter Jan Lievens. The other? We don't know who painted it. Rembrandt van Rijn, The Operation (Touch), circa 1624-25, Private collection, New York It's a very interesting thing. Maybe you get, you look at things through Rembrandt-colored glasses. You really want it to be something. And, it's not," Ocon says. Rembrandt or not Rembrandt - it will probably never be completely resolved. And, something else to consider, says curator Dennis Weller. In a given portrait, a well-trained assistant may have done the background and clothing, Rembrandt the face and hands. You might say, he sub-contracted. "When you talk about is it Rembrandt or not Rembrandt, perhaps we should re-phrase that and say: Is it Rembrandt and students of Rembrandt in the same painting?" So that does mean a painting could be 68.5 percent Rembrandt? Possibly, Wells says. " If you want to take the size of the picture and divide it up into clothing versus face, and do a percentage. But, again if you've got a Rembrandt face you've got a Rembrandt. Because that's really what it's all about. How he captured the spirit of the sitter." For this museum show, 27 authentic Rembrandts are on display. Plus discredited Rembrandts. And a few that the experts are still not quite sure of. You be the judge.