The unnamed band is pretty simple in design. The interior contains a secure microchip from Gemalto and an embedded antenna; the exterior is simply a black or white ceramic loop. The addition of any kind of decorative metal or dye would interfere with the antenna. It also won't be custom-fitted but, with 20 sizes available during its trial run, most testers should be able to find a good match. That initial group includes employees and partners, but most notably the 45 athletes sponsored by the payment provider, including swimmer Missy Franklin and fencer Ibtihaj Muhammad.

It was discussions with those Olympians that inspired the creation of the payment ring; wallets and standard wearables can be a real annoyance when you're constantly changing in and out of uniform. Decathlete Ashton Eaton specifically told Visa he wanted something he could just integrate into his daily routine and forget about. So the ring was designed not only to be inconspicuous, but also be water resistant to 50 meters and never need charging. Instead, the ring draws a tiny bit of power from the payment terminal, just enough to enable the transaction. It doesn't exchange as much data as Apple Pay or Android Pay, but it's on par with swiping your card. Visa actually provides a card with the ring, for those instances when contactless pay isn't available.

Rings have an annoying tendency to go missing, but Visa prepared for that situation too. The payment band can be deactivated from a smartphone, and thieves who find one won't be able to get anything useful out of it thanks to tokenization. That means sensitive data is replaced by a digital identifier that can be used to process payments, but doesn't actually contain any personal information.

At this point the ring is merely a prototype and won't be available to the general public in time for Rio. Instead, the Olympic Village will be a testing ground to find out how well it performs in the field. The band I saw in New York looked and felt great, and the first time I used it on a payment terminal felt magical. I waved my hand and heard that telltale "beep" of a successful transaction.

But I was lucky: Subsequent attempts were hit or miss, and I was told this was a common problem thanks to the diminutive design of the wearable. The ring works best when the full 'O' of it is facing toward the terminal; if it's held at a 90-degree position above the keypad, as it would be when you hold your palm flat, the reader doesn't pick it up. I found that holding my hand at a 45-degree angle sometimes worked. Visa plans to encourage the athletes to try a different hand position, so don't be surprised if you see a few of your favorite competitors trying out a "fist tap" the next time they need to pay for a Coke in Rio.