At Bloomsbury Manor, our reputation is built on trust and a meticulous approach to authenticating Cartier pieces, along with jewellery from other makers and brands. Many assume authenticity is as simple as checking a serial number in a Cartier boutique, but the reality is far more complex.

Cartier’s digitised inventory is not comprehensive, and vintage pieces often defy quick verification. Additionally, Cartier boutique staff are primarily trained to sell new inventory rather than authenticate vintage jewellery. This is where expert knowledge, honed over years, becomes essential.

Checking Signatures and Hallmarks

We begin by examining signatures (Cartier) and hallmarks (maker's marks and metal fineness marks)—ensuring they align with the era and place of manufacture. For example, Cartier rings purchased in France often feature hallmarks on the outside of the shank. Many 20th-century pieces bear an eagle’s head for gold or a dog’s head for platinum, but there are exceptions.

Cartier used a number of different makers to manufacture their jewellery. This adds complication because anyone looking for a single markers mark (not signature) might be confused for example when they see an H and a V in a lozenge. Read on to find out what this stands for!

Pieces bought in the UK today are typically struck with Swiss convention marks, as Cartier’s parent company, Richemont, is Swiss-based. Because Switzerland and the UK are both members of the Vienna Convention on Hallmarking, these marks are mutually recognised.

The Role of Workmanship in Authentication

Having examined hundreds of pieces, we recognise the tell-tale signs of genuine Cartier craftsmanship. We rely on magnification, extensive reference materials, and our private database to match each piece to Cartier’s historical styles.

Cartier has historically collaborated with multiple skilled workshops—such as Langlois, Georges Lenfant, and Hamard Vitau—each leaving distinct maker’s marks in lozenge, oval, or shield shapes. In vintage pieces, these marks can sometimes appear uneven or slightly imperfect, as engravers worked quickly rather than with machine precision.

Understanding Cartier Hallmarks and Maker’s Marks

Below are some examples of the many hallmarks and engravings found on authentic Cartier pieces across different periods and manufacturers. Cartier’s signature has evolved over time, and understanding these variations is crucial to identifying when—and by whom—a piece was made.

Take the iconic Cartier Trinity ring, which has been in production since the 1920s. It has been manufactured by several different workshops over the decades, each leaving its own maker’s mark. On forums, we often see discussions debating which maker’s mark is the "correct" one. The truth is, it depends entirely on when the piece was produced. This is why expert evaluation is essential—true authentication means considering all the variables in context.

Trinity Ring with classic Cartier signature, 750 (18k gold), and French ring size stamp.

Panthère bracelet with hand-engraved single line signature. Maker's mark lozenge and 750 stamp (for 18k gold).

Thin line Cartier signatures & serial number from 1996 on demi-lune bracelet with lozenge 750 stamp visible just above.

Hinge of 1950s brooch engraved with Cartier's signature & serial number—note the serifed script & alignment, characteristic of the era.

A modern-day signature—totally even, and with authentic Swiss control marks, serial number & more unique detail pertaining to just this piece.

A signature and serial number unevenly inscribed, completely consistent with late 20th century creations.

A signature that’s delicately inscribed, with spacing & proportion consistent with hand engraving from mid-century collections. This charming imperfection is part of what makes vintage pieces so special.

Despite minor engraving imperfections, Cartier’s craftsmanship remains paramount. Any jeweller producing work for Cartier adheres to the highest standards. While a signature can be copied, replicating Cartier’s level of workmanship is significantly harder.

Why Workmanship Matters Most

It’s impossible to fully describe the depth of analysis that goes into evaluating Cartier’s workmanship—it’s something that comes only with years of hands-on experience. Some of the images below offer a glimpse into how we assess quality and authenticity. While online conversations often focus on signatures, we believe a signature alone tells only part of the story—perhaps 30%.

The real signature lies in the craftsmanship. From the finesse of a setting to the way a piece wears over time, the true markers of authenticity are in the details only experience can interpret.

Perfectly precise wire work, each gold thread intertwined by hand.

Crisp screws & even claws, give an engineered precision to the look.

Totally uniform links apparent even on the reverse of this bracelet from the 1990s.

A fine hand-finished polish giving a perfect shiny black look on silverium, a silver alloy patented by Cartier in 1987.

Cartier Panthère Trinity Ring showing meticulous detail to the face of the panther.

Intricate workmanship required to create this Cartier Burmese Ruby & Old Cut Diamond Brooch from the 1950s.

Can Cartier Authenticate Your Jewellery?

It’s a common assumption that you can walk into a Cartier boutique and receive instant authentication for any piece—if only it were that simple. While recent purchases might be listed in Cartier’s current system, they do not offer a public authentication service, and vintage items are especially difficult to verify on the spot.

This is partly because Cartier’s records—dating back to 1847—have not been fully digitised. Converting over 175 years of archival documentation into a searchable format would be an immense task. In addition, boutique sales associates are trained to advise on current collections, not to examine and authenticate vintage jewellery.

That said, Cartier will (at the time of writing) verify a piece’s authenticity if it is submitted for servicing. Acceptance of a vintage item into their repair system is, in itself, a clear endorsement that the piece is genuine. The cost for this verification depends on the type of service required.

Our Commitment to Authenticity

At Bloomsbury Manor, we authenticate with diligence and expertise. Every item we sell is backed by a 30-day no-quibble refund policy, ensuring confidence in your purchase. By analysing signatures, hallmarks, and craftsmanship, and utilising Cartier’s own servicing when necessary, we uphold the brand’s legacy.