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24 October 2026 · Updated at 07:47 GMT FR EN ES Member area Log in
Certification

By number

Verify a certificate by entering its OIMAP number: format, reading the result and error cases.

Updated : October 28, 2026· 3 min read

One number, one check

Annunciation to the Shepherds: Leaf from a Book of Hours (1 of 6 Excised Leaves), Henri d'Orquevaulx (c. 1420–30)
Annunciation to the Shepherds: Leaf from a Book of Hours (1 of 6 Excised Leaves), Henri d'Orquevaulx (c. 1420–30)

Each registered work carries a unique number in the format OIMAP-YYYY-NNNNNN, repeated on its certificates with a suffix indicating their nature. Entering it in the verification service is enough to query the Registry.

Verification by number is suitable when the document is received by email, when a QR code is illegible or when you only have a reference in a catalogue or a contract.

It gives the same result as scanning the QR code. It is free, requires no account and is available at any hour.

  • Format
  • Suffixes
  • Entry
  • Result

The number in figures

4digits for the year
6digits for the sequence
4certificate suffixes
€0cost of the check

Reading a number

Example: OIMAP-2026-004281-A
ElementExampleMeaning
PrefixOIMAPIdentifies the Registry
Year2026Year of registration of the work
Sequence004281Sequence number within the year
Suffix -A-ACertificate of authenticity
Suffix -P-PProvenance certificate
Suffix -C-CConservation report
Suffix -N-NDigital certification

Entering the number

  1. Open the verification page

    From the home page or the Certification menu.

  2. Entering the number

    Upper or lower case, with or without spaces.

  3. Validate

    The result appears in a few seconds.

  4. Read the description

    Compare with the work.

  5. Keep the proof

    Take a dated screenshot if needed.

Plaque (1500s–1600s)
Plaque (1500s–1600s)
Jar with Design in Underglaze Iron (1800s–1900s)
Jar with Design in Underglaze Iron (1800s–1900s)
Mercury (Budha), from a Mandi Astrology Series, Sanju (c. 1810)
Mercury (Budha), from a Mandi Astrology Series, Sanju (c. 1810)

Frequent entry errors

Work number or certificate number

Jar with Stamped Decoration (1400s)

Work number

OIMAP-YYYY-NNNNNN
  • Identifies the work
  • Finds all its certificates
  • Result: work and alerts

Useful for checking a work.

Chemin de fer de Toulouse à Bayonne. Pont de l'Aran (en trois arches de 17m d'ouverture chacune). Situation des travaux au 21 juillet 1861, Édouard Baldus (1861)

Certificate number

OIMAP-YYYY-NNNNNN-X
  • Identifies a specific document
  • Result: certificate and validity
  • Mentions the suffix

Useful for checking a document.

Results of verifications by number in 2024

Authentic91%
Unknown6%
Work flagged2%
Suspended or revoked1%

Source: statistics of the verification service.

Case study: a number in a catalogue

A check before bidding

Situation

A collector reads an OIMAP number in an online sale catalogue.

Actions
  1. They enter the number in the verification service.
  2. The result confirms the work and the absence of alerts.
  3. They bid with confidence.
Outcome

The check takes fifteen seconds.

Evolution of the format

  1. Simple number

    Sequential numbering.

  2. Addition of the year

    YYYY-NNNNNN format.

  3. Suffixes

    Distinction of certificate types.

  4. Entry check

    Help message in case of error.

Limits of verification by number

A number does not by itself prove that the document bearing it is authentic: it proves that the number exists in the Registry. The check is complete when you also compare the displayed description with the work and the document.

To detect a photocopied or altered certificate, the document's QR code and its seal are complementary checks.

Mirror with Concentric Circles, an Immortal, and Auspicious Animals (100 BCE–100 CE)
Mirror with Concentric Circles, an Immortal, and Auspicious Animals (100 BCE–100 CE)
The Triumph of Mordecai, Lucas van Leyden (1515)
The Triumph of Mordecai, Lucas van Leyden (1515)
Turtleback Reading Lamp, Tiffany Glass & Decorating Company (c. 1895–1902)
Turtleback Reading Lamp, Tiffany Glass & Decorating Company (c. 1895–1902)

A practical tip

Seal Color Box (1662–1722)
« Enter the number yourself: never click a verification link received from a seller. »
Certification Department, OIMAP

Vocabulary of the number

Suffix
Letter added to the work number to designate a certificate.
Registry
Official database of works and certificates.
Case
Distinction between upper and lower case.
Enumeration
Systematic trying of numbers, detected and limited.

Frequently asked questions

Is the number secret?

No: it is printed on the certificate and may appear in a catalogue.

The result says “unknown”: is it a fake?

Not necessarily: check the entry, then the report if doubt persists.

Can I verify several numbers?

Yes, up to sixty per minute.

Where is the number on the certificate?

At the top right and under the QR code.

Contacts

A Palace with an Arched Bridge (A Roman Villa), Hubert Robert (1760)
A Palace with an Arched Bridge (A Roman Villa), Hubert Robert (1760)
Certification DepartmentParis — Headquarters+33 1 00 00 00 00certification@oimap.exampleMonday to Friday, 9 a.m. – 5 p.m.

Verify a number

Historiated Initial (O) Excised from an Antiphonary: The Donor, Gorus Fucci, Kneels before Christ (c. 1300–1350)

Go to online verification.

Verify now
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