Our Services - GB'S PARIS

Our Services

Scientific Expertise and Advisory for Ancient American Art

Guillaume J.A. Bresso, PhD, advises private collectors, families, institutions, and art market professionals in the authentication, study, valuation, and protection of Pre-Columbian artworks and antiquities from the Americas.

Each project brings together academic scholarship, hands-on expertise, and scientific analysis. It is conducted to the highest standards — with strict ethics and full compliance with French and European regulations.

Expertise and Advisory Services

Scientific Authentication

In-depth analysis and certification of authenticity for works from Maya, Olmec, Mixtec, Teotihuacan, Chupícuaro and other Mesoamerican and Andean civilizations. Reports integrate iconographic study, technical examination, material analysis, and scientific testing.

Forgery Detection

Identification of modern reproductions and sophisticated forgeries through visual examination, material analysis, and expert knowledge of ancient artistic techniques.

Provenance Research

Historical and archival investigation to reconstruct the complete ownership history and establish full traceability.

Valuation and Heritage Assessment

Independent market valuation for insurance, sale, estate settlement, or donation purposes.

Thermoluminescence and OSL Dating

Scientific dating conducted in collaboration with leading specialized laboratories.

Insurance and Collection Protection

Assistance in preparing insurance documentation with accredited valuations and implementing appropriate security measures for collections.

Collection Advisory

Collection inventories, conservation guidance, and long-term collection strategy.

Legal and Regulatory Framework

The trade in cultural goods is governed by increasingly stringent European and national regulations. Regulation (EU) 2019/880 on the import of cultural goods establishes enhanced requirements for traceability and due diligence, with several provisions fully in force since 28 June 2025.

In France, this is complemented by Law No. 2016-925 of 7 July 2016 on freedom of creation, architecture and heritage (LCAP Law). In this context, scientific authentication, provenance research, and documented expert reports are essential tools for legal, patrimonial, and insurance protection.

Professional Ethics

The practice of art expertise follows strict ethical principles upheld by leading professional organizations such as the Union Française des Experts (UFE) and the European Chamber of Art Experts (CEEA).

Guillaume Bresso adheres to these core principles:

Complete independence and impartiality
Absolute confidentiality and professional secrecy
Interventions strictly within his area of expertise
Scientific integrity and refusal of any unsubstantiated conclusions
Full transparency on methods and limitations

These commitments ensure clients receive reliable, independent expertise that meets the highest professional and legal standards.

Fees and Terms of Engagement

Fees are determined by personalized quotation, based on the complexity of the object or collection, the research involved, and any required analyses. They reflect the value of a high-level service that engages the expert’s full professional responsibility.

Indicative Fees – 2026 (VAT included – France)

Service	From	Percentage fee (degressive)	Details
Preliminary assessment (photographic submission)	Free	—	Initial review, no obligation
Certified written valuation	950 €	1.5% – 2.5% of estimated value	Detailed report
Full authentication expertise	1,450 €	1.8% – 3%	In-depth iconographic and technical analysis
Forgery detection and analysis	1,650 €	2% – 3.5%	Comprehensive substantiated report
Provenance research	2,800 €	2.5% – 4%	Historical and archival investigation
Thermoluminescence and OSL dating	850 € per sample	Flat fee	Partner laboratory analysis
Expertise for insurance or succession	1,200 €	1.2% – 2% of total value	Degressive according to total amount
Comprehensive collection advisory	Upon request	0.8% – 1.8%	Inventory and collection strategy

Laboratory analyses, secure transport, additional examinations or international archival research may be invoiced separately according to the needs of each case.

A detailed and transparent quotation is provided before any engagement.

References

Regulation (EU) 2019/880 of the European Parliament and of the Council of 17 April 2019 on the introduction and import of cultural goods
Law No. 2016-925 of 7 July 2016 on freedom of creation, architecture and heritage (LCAP Law)