Dear Nicolas,

Thank you for the additional information and your patience.

The presented object appears to be a painting made in oil on parquet wood with the measurements of 50 x 44 1/2 inches. The painting depicts the portrait of an elderly woman with a white bonnet, a ruff, and a black costume. This reluctant clothing marks this woman as a member of the upper class. This painting appears to be signed over the right shoulder "Rembrand v Ryn".
The facial features and partly the costume like the bonnet remind of the portrait of Aeltje Uylenburgh by Rembrandt which is nowadays in the collection of the Museum of Fine Arts in Boston (https://www.wikidata.org/wiki/Q21501685#/media/File:Aeltje_Uylenburgh,_by_Rembrandt.jpg). The painting by REMBRANDT VAN RIJN (1606-1669) in Boston is an example of the quality of the depiction of the facial features, the expression of the personality, and the details of the clothing of Rembrandt. In comparison to these named details, the facial features, the expression and the details of the clothing like the ends and structure of the ruff make a difference between these two paintings in the quality visible. The colorit of the skin and the depiction of shadow and light on the skin of the woman are not homogenous. Rembrandt worked together with a workshop and some paintings are just partly made by the artist himself. It was common in this period that the artist just painted the face and hands or he just painted the eyes. The rest of the painting was made by partly specialized apprentices.

There are three possibilities regarding the authorship of this painting.
- It is a copy by another artist after the portrait of Aeltje Uylenburgh by Rembrandt.
- It is a painting with mostly authorship of the workshop and minor details by Rembrandt or just the signature.
- It is a painting with mostly authorship by Rembrandt which was restored and partly repainted.

Because of the differences in the quality of the depiction of the facial features, the expression, and the details it is most likely that this is a copy by a second artist who belongs to the follower or circle of Rembrandt. This does not explain the signature.
Regarding the authentication, this piece needs intense further research, which can not be covered by this preliminary estimation on the basis of images. The question of authorship of Rembrandt is a difficult process and I have to mirror this in a wide estimation range.
This piece is in damaged condition and there is a crack in the wood visible in the images provided.
A fair market estimation would be between 5.000 to 20.000 USD.
This estimate is based on actual recent past recorded auction sales of comparable items. Retail "asking prices" can be higher and may vary.

Because of the differences between ensured works and the high potential value, this artwork requires further authentication research. This estimate is provided on the condition of authenticity.

With kind regards,
Georg