It is extremely unlikely that Chagall signed reproductions. The only certificate podverzhdayuschy signature can only be issued by the Fund Chagall. All the rest - it's trash. If you believe in fractions of a percent - apply to the Fund by Chagall.
After obtaining the opinion will be able to sue the sellers
>.
===
Lithographs and etchings by famous masters such as Chagall, Matisse, Miro, Picasso, are usually between 2 and 000 USD. Their work is more expensive Dali in connection with the fact that they produced their work in a smaller Number of copies. For example, Chagall lithograph printed in 50 copies (+ a few copies. Better quality) and never made more runs than constantly engaged in Dali. All of this relates to work numbered, which are signed by the authors.
Besides those, there are massive and original works, which are significantly cheaper. Typically, this lithograph printed in specialized art magazines, such as "Derriere le Miroir". In addition to the title of the journal came out more well-known magazines "Verve" (1937-1960) and "XXe siecle" (1960-1980). In whom also invested /glued original author prints.
Signed and numbered lithograph by Chagall are from 2 to 40 thousand USD. Within the 5.2 thousand lithographs are former inserts in the books.
Separately executed lithographs are usually between 6 thousand signed and numbered prints (again, from the books) are available for 1.5 - 3 thousand USD.
On the whole the author's printed graphics (printmaking) from Chagall have catalogs. True they cost significant money, because they are the original dust jacket, lithographs and directories have vkladashami original work.
Here is a list of directories:
Illustrated books (author's engravings): Cramer P. Marc Chagall.
The Illustrated Books. Catalogue Raisonne. Geneva, 1995.
Illustrated books (author lithography): Sorlier S. Chagall 's
Illustrated Books. Catalogue Raisonne. 1993.
Copyright lithography in the journal Derriere le Miroir: Maier-Preusker W.
Katalog der graphischen Werke von Marc Chagall in der Edition Derriere
le Miroir. 1950-1982. Wien, 2004. ISBN 3-900208-05-0.
Engravings: Kornfeld E. W. Marc Chagall. Catalogue raisonne de l'oeuvre
grave /Verzeichnis der Kupferstiche, Radierungen und Holzschnitte von
Marc Chagall. Volume I /Band I: 1922-1966. Bern, 1971.
Lithography: Mourlot F. Chagall. Lithographe: 1922-1957. 1960.
Lithographe II: 1957-1962. 1963. Lithographe III: 1962-1968. 1969.
Lithographe IV: 1969-1973. 1974. Sorlier C. Lithographe V: 1974-1979.
1984. Lithographe VI: 1980-1985. 1986.
Monotype: Leymarie J. Monotypes. 1961-1965. 1966. Cramer G. Marc
Chagall. Monotypes II: 1966-1975. 1976.
Posters: Sorlier C., Adhemar J. Chagall Poster. Catalogue Raisonne. 1975.
====
If you are interested in buying prints, please, maybe I can help.