Caviar has earned the nickname “black gold” for a reason.

Sterling Caviar, the oldest and biggest farm, raised caviar producer in the United States – sells 30 grams of caviar for $70 to $115, depending on the size, taste and color of the eggs. Sterling is based, in Elverta, Calif.

“It’s kind of like wine, an acquired taste,” said Sterling vice-president Bobby Renschler.

It’s a taste Juan Johnson has picked up better than most. Johnson works at Sterling tasting caviar, helping decide its classification.

“Not too salty, not too fishy – that’s pretty much the best flavors, I guess,” Johnson said.

But Johnson’s decisions have major financial ramifications at the end of a lengthy, intense process. A female sturgeon whose eggs are classified as the highest-quality caviar is worth $10,000, Renschler said. On the lower end, the fish is worth a couple thousand dollars.

Perhaps the craziest thing is that the various grades of caviar all come from the same fish – white sturgeon. And even the people who have devoted their lives to studying and raising sturgeon don’t know what kind of caviar a fish has until the ovary is removed at the end of the life cycle.

“From the outside, they all look very similar,” Renschler said. “The eggs they produce are very diverse.”

In 2017, Sterling will aim to sell 10 metric tons worth of caviar. The demand for the company’s domestic, farm-raised caviar is on the rise.

“We’ve been selling out every year, for the last 2 to 3 years,” Renschler said.

Sterling sells caviar all over the world, in countries such as Dubai, Hong Kong and Australia. Locally, the company supplies caviar to restaurants including the French Laundry, in Yountville, and Sacramento’s Ella.

And while Sterling’s team is working hard to keep up with the demand and refine the process, it continues to be a challenge.

“It always seems like [the sturgeon] are throwing surprises at you,” Renschler said. “Just when you have something figured out, something changes.”