Changeling

Changelings or color changelings are stamps where the ink color has been altered chemically, often in unexpected colors. This can be due to fading or other aging effects including oxidation. The latter was often caused by exposure to coal fumes containing sulfur from home heating.

Sometimes a stamp's ink color has been completely changed, other times a part has been changed, or there is a gradient of color. If you have an older stamp where catalogs do not list the color you have, chances are very good that you have a changeling of some kind. Orange/vermilion engraving inks will often turn to brown and even black.

This all requires that a stamp, mint or used, should be reasonably fresh so as not to have been obviously affected by aging or chemicals. Even so, chemicals used to bleach stamps can often cause unintended color changes.

 File:CGH Table mountain x2.png|The left stamp is not rose pink but faded badly. The yellowing is a clear sign that it has been badly stored over the years. File:GB KEVII 5dx2.png|Changeling on the left, normal on the right 

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