Delft tiles like the ones found by Ivy Calvin and his son are still circulating today — and the ones the Calvins found in their locker are more valuable than other options. Back when artists were first creating the tiles, they could either hand-paint them or use a stamp to create a textured look, and the hand-painted tiles are worth more. As Pops says, "A little more effort means a little more money."

Antique Delft tiles don't run cheap, as the Calvins learn during their consultation. But for those who can afford them, they make great additions to modern interior design. Back in the 1500s, the tiles were originally created to festoon sooty fireplaces: Since the tiles are impervious to heat and easy to wipe down, tiling a fireplace with Delftware was not only functional but fashionable. As homeowners realized the tiles were also waterproof, they began to accessorize other parts of their homes with them.

Delftware fell out of fashion towards the end of the 18th century and production slowed soon after. But today, tiles in the Delft style can be purchased on sites like Etsy and Wayfair, and are often used to create kitchen backsplashes or incorporated into bathroom decor. Some modern artists are even subverting the style by creating racy images that pay homage to the irreverent iconography found in the originals. But for the Calvin men, Delft tiles will always be remembered as a lucrative find.