NATCHEZ — What’s purple, green, sometimes filled with cream and could be used to teach basic economic principles?

Here’s a hint — it often comes with beads and doubloons.

No rule exists that says king cake can’t be served year-round, but most of the time bakeries just don’t push them.

But when Mardi Gras rolls around?

“The day I advertised we had king cakes, we had eight orders,” Donut Shop Owner Jason Tyson said.

One principle that could apply is the concept of artificial market scarcity, which applies when the means to produce something exist full time, but producers — in this case, bakers — choose not to make the product.

A high demand for a product then develops because of its relative unavailability most of the time.

“Pretty much immediately when we put the king cake out on the counter, it is one of those things that people only see once a year, so they start buying it,” Uptown Grocery Manager Gia Shafer said.

“We put them out, and it catches people’s eyes. It has been a year since they have had them, and they instantly want a piece.”

But the other principle that comes into play is simple supply and demand. In this case, the demand may only exist for a short window — from shortly after Christmas until the beginning of the Lenten season

“Very few places make them year-round, but I think what makes people want to buy king cakes at this time of year is more the tradition of the season itself,” Tyson said. “Everybody likes Mardi Gras time.”

Whatever the driving factor, Edna Welch — owner of Edna’s Cake Creations — said she’s thankful for the king cake boost. The multi-colored pastries make up approximately a third of her business during the Mardi Gras season, she said.

“This time of year can be kind of slow, and king cake keeps us going during the slow months,” she said. “When there is demand for something, you have to offer it.”

How that demand is met depends on the baker.

In Shafer’s case, she actually offers king cakes year-round, but starting around Jan. 9 every year, she starts gearing up for the heavy demand, whipping up a special-made icing to go in the cinnamon-flavored sweet bread that she’ll braid and fill with apple cinnamon, cream cheese or blueberry — among others — creams.

In Shafer’s case, meeting the market also means offering a novelty.

“We have a bacon praline pecan king cake, which I know sounds a little strange, but when you taste it, it’s great,” she said.

Tyson offers cakes shaped like traditional pound cakes with slits in the top so the filling on the inside — raspberry, lemon, blueberry, strawberry, Bavarian cream and cream cheese among the flavors offered — moves to the outside.

But he also offers a king cake donut — a traditional glazed donut topped with king cake icing and stuffed with the Mardi Gras-themed fillings.

“We can’t keep them in the window,” he said. “As soon as we make them, in 10 or 15 minutes we need more.”

In Welch’s case, she offers masked-shaped cookies and other items for Mardi Gras to go along with the cakes, which she tops with purple, yellow and green sugars, bead necklaces and doubloons.

For those who want fillings, she offers praline, caramel apple, cream cheese, strawberry and blueberry flavors, among others.

Welch uses a traditional sweet bread recipe, and sometimes rolls pecans into it, but Welch’s offering is ultimately  a visual appeal to seasonal tradition.

“When I make the king cakes, I try to make it look like a crown, which is what it originally was supposed to look like,” she said.