I'm pretty sure that means that the Amex is contactless, you can just wave or tap over a terminal and pay. I just recently read here that the Amex with contactless has a matte plastic back vs metal, like the non contactless version.
I wonder if that means the Chase card is contactless as well? Or if they just use a different version/brand/model chip?
The contact only Platinum doesn't have a metal back; it is actually transparent, back printed plastic. The magstripe is part of the plastic back panel.
My Amex Platinum uses an eight point contact like Chase.
No, it doesn't. Look closer. In that photo the Amex is a 6-contact chip and the Chase is an 8-contact chip (if you don't know what you're looking for, it actually would give the appearance of having 10 - not 8 - unique segments, but 4 of them are not defined or connected to anything - they're purely decorative, there are only 6 actual contacts - which is why the chip is placed slightly higher on the card than on an 8-contact chip of the same size - so the six actual contacts line up correctly).
Until recently, contactless required a larger contact pad, but not necessarily 8 contacts.
8 contacts are needed for programming certain OSes, though I can't remember off the life of me which ones. Once the card is delivered to you, the difference is irrelevant.
The contacts, and their position are standardised by ISO 7810-1.
However the standards only define a minimum area for the contacts and their seperation, so vendors sometimes use that leeway to incoperate logos or other art into the contacts (HID does this, and ZietControls used to.) The top six pins handle almost everything the card will ever do, Two of them are power, two are data, and the remaining two are reset (think reboot) and programming power (mostly not used now, older technologies needed higher voltage to write).
The bottom two pins are reserved for per-vendor functions, and are usually either not connected internally, or are connected, but have no function. The notable exception is some cards that support USB, and can use a simple passive adapter instaed of a real reader (this is not typically not used for payment cards)
Some intersting things to note, both saphires used 8 pin contacts, but they are from different manufacturers, and the CSR looks more angular. Amex seems to have embedded a 6 pin contact into a larger structure for the platinum, possibly to avoid issues with the contacts touching the metal card, or simply as a design choice.
Speaking of Amex, the everyday line is made of clear plastic, so you can see the back of the die, as well as the contact bonding points. If you use a maginfiying glass, you can also see the miniscule gold bond wires. (The everyday has a more 'scalloped' look to it's contacts)
I was told before that the extra two are used by Chase ATM's. Their debit cards are 8-pin as well.
How am I supposed to go to the strip club with my fake AMEX Centurion with the chip if y'all posting pics of the latest technology?
Got to find a new way to be a player the day after I thought I was up-to-date.