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

Certificates of authenticity

The OIMAP certificate of authenticity establishes, through independent expertise and scientific analysis, that the work is indeed the one claimed.

Updated : October 28, 2026· 4 min read

Pages in this section

Mercury (Budha), from a Mandi Astrology Series, Sanju (c. 1810)ConditionsWhich works can be certified, who can submit a case and when a request is inadmissible.› Plaque (1500s–1600s)File to provideComplete list of documents, photographs and information to attach to an application for a certificate of authenticity.› Sweet Melancholy, Joseph-Marie Vien (1756)TimeframesDuration of each step of an application for a certificate of authenticity and factors that can lengthen or shorten it.›

Establishing who made the work

Portrait of a Woman, Gerard ter Borch (c. 1665)
Portrait of a Woman, Gerard ter Borch (c. 1665)

The certificate of authenticity answers a simple and decisive question: is this work really by the artist, workshop or period stated?

It is the act most requested at the Desk: 8,420 certificates have been issued since the Registry was created. It is required by most auction houses, insurers and museums before any major transaction.

The expert assessment combines a specialist's eye, documentary research and proportionate scientific analyses. It is carried out by an accredited expert, independent of the applicant.

  • Expertise
  • Analyses
  • Reasoned opinion
  • Registry

Authenticity in figures

8,420certificates issued
4 to 8weeks timeframe
€900indicative price excl. VAT
360accredited experts

Source: OIMAP Observatory, 2024.

Three pages to prepare your application

Teapot with Landscape and Imperial Poem, Chen Hanwen (1762–95)EligibilityConditions

Eligible works, exclusions and conditions to be met by the applicant.

›Scenes of Witchcraft: Morning, Salvator Rosa (c. 1645–49)PreparationFile to provide

Documents, photographs and information to gather before submission.

›Document Box (Ryōshibako) with Chrysanthemum and Plum (lid) (late 1800s-early 1900s)CalendarTimeframes

Duration of each step and factors that lengthen a case.

›

What the certificate attests

The certificate attests that, on the basis of the evidence available at the date of the assessment, the work described is by the hand of the artist, of his or her workshop, or of the period stated. It identifies the work unambiguously: dimensions, technique, signatures, photographs, OIMAP number.

It states the degree of certainty of the conclusion, the list of analyses carried out and the expert who signed the opinion. It is sealed, given a QR code and entered in the Registry.

Portraits of the Qianlong Emperor and His Twelve Consorts, Giuseppe Castiglione (1736–70s)
Portraits of the Qianlong Emperor and His Twelve Consorts, Giuseppe Castiglione (1736–70s)
Carved Lacquer Scroll Box (1736–95)
Carved Lacquer Scroll Box (1736–95)
Still Life with Vegetables, Partridge, and a Jug, Adolphe-Félix Cals (1858)
Still Life with Vegetables, Partridge, and a Jug, Adolphe-Félix Cals (1858)

What a certificate contains

Anatomy of a certificate of authenticity
HeadingContent
IdentificationOIMAP-YYYY-NNNNNN-A number, artist, title, date, technique, dimensions
ConclusionDegree of certainty: authentic, attributed, workshop, school, not authentic, undetermined
ExaminationsList of visual examinations, imaging and analyses carried out
SourcesCatalogues raisonnés, archives and comparison works
SignatoriesExpert, committee chair, date of issue
SecurityOfficial seal, QR code, fingerprint recorded in the Registry

How authenticity is established

  1. Visual examination

    The expert observes the workmanship, the brushwork, the materials, the signature and the inscriptions.

  2. Documentary research

    Catalogues raisonnés, correspondence, workshop archives and old sales.

  3. Imaging

    Infrared reflectography, UV fluorescence, radiography: pentimenti, restorations, underlayers.

  4. Laboratory analyses

    Pigments, binders, supports, dating if necessary.

  5. Reasoned opinion

    The expert concludes, stating the sources and the degree of certainty.

Value of the certificate

Authenticity or provenance: what is the difference?

Seal with Two Qilin Playing (1849)

Certificate of authenticity

Who made the work?
  • Examination of the object itself
  • Material analyses and stylistic comparison
  • Conclusion on attribution

To be requested before a sale or insurance.

Portrait of a Woman, Anna Claypoole Peale (1820)

Provenance certificate

Whose hands has it passed through?
  • Study of the object's history
  • Archives, invoices, inventories, exhibitions
  • Conclusion on the chain of ownership

To be requested to secure ownership.

Outcomes of authenticity assessments in 2024

Authentic75%
Attributed to14%
Workshop or school7%
Not authentic4%

Share of the 8,420 opinions issued. Source: OIMAP Observatory.

Authenticity at OIMAP

  1. First certificates

    Issued by the experts of the founding States.

  2. Accreditation

    Creation of the accreditation of experts and of the code of ethics.

  3. Common protocol

    Directive No. 2019-07 sets the authentication method.

  4. 8,420 certificates

    A 9% rise over one year.

Nini in the Garden (Nini Lopez), Auguste Renoir (1876)
Nini in the Garden (Nini Lopez), Auguste Renoir (1876)
Letter Box, Ogata Kōrin (1700s)
Letter Box, Ogata Kōrin (1700s)
Portrait of a Woman, John I Smart (c. 1772)
Portrait of a Woman, John I Smart (c. 1772)

Case study: an attributed drawing

A nuanced attribution

Situation

A collector wishes to have a drawing attributed to a Japanese master of the print certified. The signature is partly effaced.

Actions
  1. The expert, a specialist in graphic arts, examines the paper and the ink.
  2. Imaging reveals an old collector's stamp.
  3. Comparison with three sheets from the same series confirms the style.
Outcome

“Attributed to” certificate, with a reasoned reservation on the signature: sufficient for insurance, not for a sale at the master's price.

A point of method

Carnet (1863–1865)
« One does not authenticate a work against the verdict of the materials. Style proposes, matter disposes. »
Dr. Amara N'Diaye, chair of the certification committee

Vocabulary of authenticity

Attribution
Linking a work with an artist, with or without certainty.
Catalogue raisonné
Critical and complete inventory of an artist's work.
Pentimento
Visible alteration made by the artist during execution.
Infrared reflectography
Imaging that reveals the underdrawing of a painting.

Frequently asked questions

Does a certificate of authenticity have a period of validity?

No, it is unlimited, unless a new fact arises that might call the conclusion into question.

Can I have a work by a living artist certified?

Yes, with the participation of the artist or their successor in title, who confirms the attribution.

Does OIMAP certify the value of the work?

No. Valuation is a matter for other professionals; the certificate concerns authenticity.

What if the certificate is challenged?

A third party may seize the Arbitral Tribunal. The certificate remains valid until a decision is made.

Useful documents

Contacts

Small Mosque in the Kaiserbagh, Felice A. Beato (1858)
Small Mosque in the Kaiserbagh, Felice A. Beato (1858)
Certification DepartmentParis — Headquarters+33 1 00 00 00 00certification@oimap.exampleMonday to Friday, 9 a.m. – 5 p.m.

Have a work certified

Nymphs and a Satyr (Amor Vincit Omnia), Nicolas Poussin (c. 1625–27)

First check the conditions, then open your case.

See the conditions
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