Changeling, Color Error, Color Missing

*** Moved by Staff to a more appropriate forum. ***
I have been following the different posts on these items and I think I have a pretty good grasp of the differences in the basic terms (including color shifts). But for the identification of color error (which could be missing color, or wrong color) it would be especially difficult to determine 'missing color' on a single stamp (without adequate magnification). But if one were to have a complete sheet (more in the modern era) since the plate number of modern issues is inclusive of the colors of the issue. Different colored number for each plate #. 11111 vs 12111. If the color was truly missing it would also be missing (entirely) from the plate # providing a gap or a 'short #'. (yeah I know, it isn't that easy).

ELIGIES ----I understand your question ,but it would be better if you ask your question in the section for U.S. modern stamps . From the plate number it looks like a U.S. question for a sheet or a coil stamp.

Color missing errors occur when ALL of the color is missing from a stamp. Thus a stamp maybe a color missing error but the corresponding multi-color plate number may or may not be affected. It really depends on the mechanism involved as to why a color is in fact missing. Of course if the colored plate number is on the stamp itself, then the missing color would be missing from that plate number.

okay (to both) thanks for the response

The Linn's Stamp News website posted this past week a news item of an expertization certificate issued as genuine for a magenta color missing, on the last stamp of a strip of seven 18c Washington coils (Scott 2149 from 1985). The strip's stamps show a progression as evidently the ink supply became starved.
If the plate number were on any of the stamps but last, it might show the magenta digit if magenta was evident in the design, but not appear on the last stamp if that stamp had the plate number (being devoid of magenta ink, per experts' opinion).