Delta Air Lines launched its redesigned credit cards Thursday with revamped benefits and one more surprise — the two most expensive cards will be made of metal.

All four tiers for the consumer cards — blue, gold, platinum and reserve — have a new look. Platinum and reserve will be made of metal versus the traditional plastic.

Metal credit cards are growing in popularity, with dozens of premium cards on the market now made of the heavier material. After all, nothing says, "I've got this one" like throwing down a metal credit card on the restaurant table.

Existing cardholders won't get the redesigned cards until their current one expires, but eager customers can order a new one sooner by requesting a card replacement through their online American Express account.

After researching what its cardholders most valued, Delta in September announced changes to rewards and points accrual, which are now effective. As we reported last fall:

Delta believes its blue and gold card members are more cost-conscious and less frequent travelers who care most about earning miles to offset ticket prices. Its platinum cardholders are loyal to Delta, but want to get to their travel rewards quicker. And its reserve members want to earner elite status faster so they can enjoy the luxury amenities.

The airline's gold, platinum and reserve cardholders will earn more points on daily purchases, such as restaurants and supermarkets.

There are, of course, a few trade-offs. Everyone will pay a higher annual fee. (Blue card holders are the exception as their card's annual fee will remain $0.) The annual fee will increase from $95 to $99 for gold, from $195 to $250 for platinum and from $450 to $550 for reserve.

Gold cardholders will no longer have the option to pay $29 for its airport lounges or the ability to use their purchases toward Medallion Qualifying Dollar (MQD) waivers, which is a path to elite status. Delta declined to say exactly how many of its gold members used these two perks, but said less than 5% used the Sky Club access and less than 1% used the MQD waiver.

Platinum members will still have lounge access, but the fee per visit is increasing from $29 to $39. Delta is also giving these cardholders either a Global Entry or TSA PreCheck fee credit.

As for reserve members, they now have access to the highly-exclusive American Express Centurion Lounge (in airports where available), and get two one-time guest passes to Delta's standard Sky Clubs each year. Reserve cardholders can also earn a 15,000 medallion qualifying miles (MQM) boost four times a year, which is twice as often as currently offered.

The airline is temporarily offering sign-up higher bonus miles along with the launch for all seven of its cards (four consumer tiers and three business tiers). More details about the changes and bonus miles are available here.

Kristen Leigh Painter • 612-673-4767