NFC Ring

At a glance

• Body: zirconia ceramic in black or white, pressed and sintered, then CNC-machined and polished.
• One chip per ring: NTAG213, 215 or 216 for phones, MIFARE Classic 1K or 4K for 13.56 MHz access readers, or ATA5577 for 125 kHz locks.
• Sealed: the chip and coil sit inside the ceramic body.
• Sizes: US #6 to #15, made to order; ceramic cannot be resized after firing.

How an NFC ring works

An NFC ring is a passive RFID transponder shaped as jewellery. A small coil antenna and a chip sit inside the ring body. They have no battery: the reader's field powers the chip for the fraction of a second the ring is held against it, and the ring answers with its identifier or with the data stored in its memory, exactly as a card or a key fob would. Everything that decides whether the ring "works" is therefore the same as for a card: the chip family, the frequency, and what the reader on the door, the turnstile or the phone is able to read.

The body is zirconia ceramic for a practical reason, not only for looks. Ceramic is an electrical insulator, so the reader's field passes through it to the coil. A solid metal band would shield the coil and absorb the field, which is why metal NFC rings on the market need a ceramic or resin window for the antenna. The all-ceramic body gives a full-circumference finish, resists scratching better than plated metal, contains no nickel, and is unaffected by water, sweat or hand sanitiser.

Choosing the ring body material

The chip decides what a ring can do; the body material decides how it wears and how well it reads. Because the reader's field has to pass through the body to reach the coil, the material is a radio choice as much as a cosmetic one. The standard ring on this page is zirconia ceramic, and other bodies can be specified per project when the look or the budget calls for it.

The practical lesson is that any solid metal band needs a non-metal window for the coil, and even then reads at a shorter distance, while ceramic, wood and resin let the field through the whole body. If a metal look is essential, plan for the window and test the read on your own reader; if read reliability matters most, a ceramic, wood or resin body is the safer specification. Whichever body you choose, the MIFARE Classic card and T5577 card pages explain how these chip types work.

Chip options: NTAG, MIFARE Classic or 125 kHz

The ring takes one chip. Choose it by what has to read the ring, because the three families below are not interchangeable: a reader built for one does not see the others.

The NTAG family is the choice when the ring is a personal object: a tap shares a contact card or a link, opens a page or starts an automation on the wearer's phone. MIFARE Classic and ATA5577 are for buildings: they make the ring a credential on a system that already exists. The six chips in the table are the standard options.

Using an NFC ring on a door or a lock

The question we receive most often is whether a ring will open a particular door. The answer depends on the reader, not on the ring, and comes down to three checks.

1. Frequency. 125 kHz proximity readers and 13.56 MHz MIFARE readers are different radios. If your building issues 125 kHz fobs, the ring needs the ATA5577 chip; if it issues MIFARE cards, it needs MIFARE Classic. The key fob guide explains how to tell the two apart from the credentials you already carry.
2. How the system enrols credentials. Most access systems accept any new credential of the right chip type: the administrator presents the ring at the enrolment reader and the system stores its serial number (UID) against the user. This is how a ring joins a system that only knows cards. Systems that write their own keys and data to the credential, such as many hotel locks and some transit and campus systems, may reject a blank ring; check with the system vendor first.
3. Reader geometry. The coil in a ring is a fraction of the size of the antenna in a card, so a ring reads at a shorter distance than a card, 1–5 cm depending on the reader. Rings read reliably on flat wall readers and on door handles when the top of the ring faces the reader; recessed readers with a small antenna area may need the hand to be placed deliberately. Ask for samples and test on your own hardware before ordering a batch.

Because the ring carries the same chip type as a card, what the MIFARE Classic card and T5577 card pages say about UID enrolment, sector keys and 125 kHz formats applies to the ring as well. We encode rings to the identifiers or data you supply for a system you administer; we do not duplicate credentials for systems you do not control.

What an NFC ring cannot do

• Contactless payment. Paying with a ring needs an EMV secure-element chip personalised and issued by a bank or its tokenisation partner, not a blank NTAG or MIFARE chip. Our rings are not payment rings and cannot be turned into one.
• Long-range reading. 1–5 cm is the working distance. A ring cannot be read while the hand is in a pocket or from across a room.
• Two frequencies in one ring. A ring carries one chip. If your site mixes 125 kHz and 13.56 MHz readers, decide which system the ring will serve or order two rings.
• Holding secrets. A ring with NTAG213 can carry a link to a digital business card or a room-service menu, but it cannot host applets, bank keys or a transit purse.

A public side and a private side: two-chip rings

The standard ring carries one chip. Buyers sometimes ask for a single ring that both shares a link and opens a door: an outward, "public" NTAG chip tapped against the back of the hand, and an inward, "private" MIFARE Classic chip presented when the palm turns to the reader. Fitting two coils in one narrow band is a feasibility question to raise per project, not a stocked option. Two 13.56 MHz coils set that close together can couple and detune each other, so the construction has to be prototyped and each chip validated on its own reader before any quantity is committed. Tell us the two chips you have in mind and we will confirm whether it is workable for your case.

Two limits apply even where it is feasible. Both inlays would be 13.56 MHz, so a dual-inlay ring cannot bridge a 125 kHz reader — that remains a separate ATA5577 ring. And a payment credential is not one of the options: neither inlay can be a bank's secure element, so a dual-inlay ring is not a payment ring. Treat it as a specify-per-project request: tell us the two chips, which faces out and which faces in, and test a prototype on both the phone and the access reader before ordering a batch.

Sizes and how to measure

The ring is made in US sizes #6 to #15. The inside diameters below are the sizes the rings are produced in, as shown in the size chart; other sizes can be produced as a custom order.

Circumference is what European and ISO 8653 ring sizes state, so the third column is the one to compare with a jeweller's sizing. To measure at home, wrap a strip of paper around the finger at the knuckle the ring must pass over, mark the overlap and measure the length in millimetres. Ceramic cannot be resized after firing, so when a measurement falls between two sizes, choose the larger one.

Durability and care

Zirconia ceramic is harder than steel and keeps its polish for years; the trade-off is that it is brittle rather than ductile, so a fall onto a stone floor can chip it where a metal ring would dent. The chip and coil are sealed inside the ceramic body, so the ring can be worn while washing hands, swimming or showering. The sealed body tolerates everyday hot water, hand-washing and a shower; avoid extreme or sustained heat, and keep it away from a jeweller's torch. Sunlight, chlorine, salt water, sweat and hand sanitiser do not affect the ceramic or the chip.

Before you order

• Chip: NTAG213, NTAG215 or NTAG216 for phones; MIFARE Classic 1K or 4K for 13.56 MHz access readers; ATA5577 for 125 kHz locks.
• Sizes and quantity per size, in black or white. Colours and inlaid finishes other than plain black and white, such as those in the photos, are quoted per order.
• Encoding: none, when your system enrols each ring by its UID; one NDEF record (URL, vCard or text) per ring; or data for a system you administer. Each ring we encode is read back afterwards, and a data report in Excel, CSV or XML goes out with the encoded order (encoding service). Whether a UID list comes with the rings is agreed in the quotation.
• Samples: one ring per chip type to test on your readers before the batch. Ceramic rings are made to order, so allow additional lead time — confirmed in your quotation — and test a sample before committing to quantities.

What Proud Tek makes and supplies

We produce the ceramic ring and encode the chip. We also make the matching credentials for the same systems: MIFARE Classic cards, 125 kHz proximity fobs, ABS key fobs, DESFire tags and NFC business cards. We do not supply access-control readers, locks or software. For encoding and testing 13.56 MHz rings at a desk, the ACR122U and the µFR Classic CS under RFID readers read the NTAG and MIFARE Classic chips listed above; neither reads the 125 kHz ATA5577.