If you bought a wooden chess set after watching "The Queen's Gambit," the price you paid was most likely dictated by just four pieces.

The knights alone can account for as much as 50% of the cost of a nice wooden set. While the rest of the pieces can be machine-made, the knights are carved by hand to resemble the head of a horse, a tedious process to make sure all four are exactly the same.

The knights in the set used in World Chess Championship matches ($310 for the pieces and $220 for the board) were inspired by a horse carving from the Parthenon in Athens, Greece, said Ilya Merenzon, chief executive of World Chess, the company that licenses the rights to the matches. The process of creating the set when it was redesigned in 2013 required extensive back-and-forth communication with carvers in India to discuss minutiae like the horse's smile.

About 10 people specialize in carving knights for the World Chess sets, Merenzon said. It takes about two weeks to produce 100 sets, with a set of knights requiring about six hours to carve, he said.

Chess-set sales spiked 125% after the October premiere of "The Queen's Gambit," a Netflix show about an orphaned chess prodigy, Beth Harmon, who crushes the male-dominated game. Many sets sold out before Christmas.

The House of Staunton in Alabama, one of the world's largest chess retailers, offers wooden sets with relatively simple knights, such as the $129 tournament-style set in boxwood and rosewood, as well as sets with more detail. They go all the way up to a luxurious $5,995 set in "antiqued" boxwood and ebony and featuring intricate horses.

In the higher-end sets, "you can literally see the teeth carved into the horse's mouth," said Noelle Kendrick, the House of Staunton's business development director. "They are extremely detailed. You can see the mane, the rivets of the mane, if it has a flowing mane."

The ornamentation isn't strictly decorative. In tournament play, milliseconds matter, and so does how a piece fits into your hand, Merenzon said. This is particularly true in the especially fast-paced games that can be used to break ties at tournaments: "blitz"-style games, which generally last less than 10 minutes, and "rapid" games, in which players have 25 minutes to make all their moves. The players tend to move their pieces and press their clock in one swift motion.

If you drop a piece and press the clock before standing it back up — effectively cutting into your opponent's time — you could lose the game under some tournament rules. At a 2016 tournament put on by India's league for professional players, grandmaster Abhijeet Gupta lost the chance to advance after dropping his queen in a tiebreaking blitz game.

"That's why expensive, hand-carved pieces are used in the championship," Merenzon said. "The pieces are also weighted. They feel significant and kind of special."

If you don't want to spend $150 or more, there are more basic wooden sets, like those from big-box retailers. The knights are produced by machines and are more in the style of a Pablo Picasso than a Leonardo da Vinci.

"When you shop for chess sets," Kendrick said, "you find yourself almost solely focused on what the knight looks like. It's the only piece that has a real significant difference."