Most mail-order offerings of artworks today are for prints. While all prints tend to be marketed as "original," only certain kinds are deemed by professional art dealers as having any intrinsic value.

Nicholas Stogdon, head of the art print department at Christie's auction house, defines an "original print" as a process "in which the artist himself works on it and is involved in all aspects of its production."

Original prints would include:

* Etchings, which require an artist to make the plate from which impressions are taken.

* Lithographs, because the artist must draw directly onto the stone from which impressions are made.

* Reproductive prints, in which an artist or craftsman makes an etching or lithograph from a painting done by someone else.

Colotypes, on the other hand, are photo-reproductions of a work of art: a photograph of a painting. Because this kind of print generally has the least direct involvement by the artist, it should cost considerably less than an etching or lithograph.

While colotypes sometimes are marketed with the claim, "Signed and numbered by the artist," signatures on colotypes generally do not increase their value (although the prices often are greatly inflated by this enticement).

"Artist proofs" and "limited edition" terms may be used (rightly or wrongly) to justify a larger price for what otherwise might be inexpensive works:

* "Artist proofs"--The first 10 percent of a print run. Corrections are made directly on the print, colors added and placement of the image on the paper sometimes adjusted. One assumes that work on the rough cut is by the artist and because it involves direct artistic activity, may be worth more than remaining prints.

The artist may not be involved, however, or the print may be a colotype, in which cases there is no particular reason why its price should be greater than any other prints in the edition.

* "Limited edition"--The biggest catch phrase. Never pay original art prices for a print unless you have in writing from the publisher: number of prints in the edition, whether any future editions are planned, whether any prints have been made from the particular image, name of the printer and whether the plates are still intact.

"Limited editions" often are limited only in their claim.