Authenticating a Renoir painting requires research. It can no longer be done by a single expert relying on his memory. Too many mistakes were made in the past.
Authenticating a Renoir painting requires forensic studies and analyses and scientific tests of materials.
Authenticating a Renoir painting requires access to French museums, French art libraries, French archives, because there is more material about Renoir in France than anywhere else.
Authenticating a Renoir painting requires multi-spectral photography, x-rays, ultra violet, infrared, hyper high resolution, digital image analysis software.
Authenticating a Renoir painting requires advanced education in art history and years of authentication practice and experience.
If you have a Renoir that is perhaps a new discovery, or a long lost, or long hidden away, or stolen, or looted painting, that has just resurfaced, we have the means, the resources, the experts, the advanced education and the experience, to authenticate it, certify it, issue the COA and appraise its value.
It you want to sell it, we have the buyers, the connections, the clients who are looking to buy.