JetBlue Mint — the airline’s business class product — was first introduced back in 2013.At the time, the airline’s business class was only available on the hotly competitive routes between New York and both Los Angeles and San Francisco.Since then, the Mint footprint has grown to include more routes. Additionally, JetBlue has continued to invest in its business-class offerings including revamped menus, new amenities and even an all-new product with direct aisle access.Want more airline-specific news? Sign up for TPG’s free biweekly Aviation newsletter.For years, the only way to score a seat in Mint was to buy one with cash or with TrueBlue points (often at an unfavorable rate relative to an economy redemption). Nowadays, you can redeem American AAdvantage miles or Emirates Skywards for JetBlue Mint, though the latter redemption option has been temporarily unavailable since last month.However, did you know that you could also score a discounted Mint upgrade at the gate?Although the airport upgrade option has been around for a while, JetBlue just codified it on its website and terms and conditions this week.As part of the update, flyers can now get a better sense of how the upgrade program works and what’s included (and what’s not).Perhaps most importantly, JetBlue notes that all types of tickets are eligible for a last-minute upgrade to Mint. This includes all “core,” or economy, fares purchased with cash, TrueBlue points or with a mix of cash and points.Sign up for our daily newsletterEmail addressSign upI would like to subscribe to The Points Guy newsletters and special email promotions. The Points Guy will not share or sell your email. See privacy policy.(Photo by Zach Griff/The Points Guy)Moves to Mint are exclusively available at the gate. They’re honored on a first come, first served basis, pending availability. So, if you’re hoping to purchase an upgrade, it may make sense to arrive at the airport a bit earlier than usual.Note that you can’t purchase upgrades during check-in (either at the airport or online), though I imagine that could change in the future as the airline looks to expand its revenue steam from ancillary fees.Once you’re at the gate, you can ask the gate agent if there are any Mint seats left. If there are, you’ll be quoted a price and can purchase the upgrade using a credit card.Unfortunately, you can’t redeem TrueBlue points to move to Mint at the airport. However, if you’re paying with one of TPG’s top recommended travel cards, it’s possible that you might be able to redeem credit card points to “erase” the upgrade charge from your statement, though the redemption value may not be great.(Photo by Zach Griff/The Points Guy)If you do decide to upgrade, you’ll receive all of the same onboard perks as any of the other full-paying Mint customers. This includes a multi-course meal with a selection of cocktails and wines, as well as access to free entertainment and Wi-Fi.You won’t, however, earn any additional TrueBlue points for the upgraded fare, nor will you receive any airport benefits (such as free checked bags or priority security). If you already paid for a checked bag based on your original fare, you won’t receive a refund if you move to Mint.The biggest question: How much does it cost to upgrade to Mint?Well, that’ll vary based on the destination, direction and day of the week, JetBlue says, without divulging any further details.So, if you’re looking to upgrade your next JetBlue flight, be sure to ask the gate agent if there are any Mint seats left.