In just a few minutes, one art collector may have earned more credit card rewards than most people will in a lifetime.

Billionaire art collector Liu Yiqian paid $170.4 million (one of the highest prices ever paid at an auction) for Amedeo Modigliani’s “Nu Couche” on Monday. He plans to pay for the painting with his American Express AXP, +0.84% Centurion card, a card for high-net-worth spenders that has no official credit limit, according to news reports.

Last year, the same collector purchased a $36.3 million porcelain cup, reportedly with his American Express Centurion card, Bloomberg News reported at the time.

While American Express didn’t confirm that Yiqian put the painting on the card, experts say that it is possible to make a huge purchase like this on a card. “In theory, it’s possible to put a ($170 million purchase) on an American Express card,” American Express spokeswoman Elizabeth Crosta told the Associated Press http://bigstory.ap.org/article/4d4647467f474c19be49307e9b4127cb/how-fly-free-forever-put-170-million-your-amex. “It is based on our relationship with that individual card member and these decisions are made on a case-by-case basis, based on our knowledge of their spending patterns.”

Often, you will need to get pre-cleared by the card issuer before doing so, says Ben Woolsey, the president of CreditCardForum.com, and of course, the merchant would have to be willing to accept that form of payment for such a large purchase. But “it’s possible in some cases with certain ultra-high-net-worth people,” says Woolsey.

If Yiqian did use the same credit card for this painting as he had in the past, the points he could have earned would be staggering. Sean McQuay, a credit card analyst at NerdWallet, says that an American Express Centurion cardholder (which Yiqian reportedly is) earns one point per dollar spent and the points are worth about one cent apiece. This means that if he bought a $170.4 million painting, he’d be looking at rewards worth more than $1.7 million, Woolsey says.

He could get a variety of things for those rewards, including $1.7 million in gift cards or statement credits. But because of better points redemption rates, it might be an even better bet to trade them in for flights and hotels. He could redeem those points for more than 1,000 round-trip first-class plane tickets from Beijing to New York, says Woolsey. “That could potentially be worth over $7 million,” he says.

The American Express Centurion card, targeted to very high net-worth consumers, has a $7,500 initiation fee and a $2,500 annual membership fee. American Express has not yet responded to our request for comment on Centurion rewards.

This story has been updated.