1893 was normally printed in ultramarine, but a handful were printed in blue, a shade with distinctly more green; these are worth in the US$10,000 range instead of the usual $10. Inks may also be diluted or applied more thinly, as for instance the World War I stamps of Germany and World War II stamps of the United Kingdom. It can also happen randomly, if a printing plate is accidentally under-inked. Ultraviolet light is destructive to a great many pigments, and can cause considerable lightening. In addition, some countries have used water-soluble materials known as fugitive inks to prevent postage stamp reuse. Stamps of this type may be much lighter in color after being soaked. Some dramatic color variations occur as a result of chemical action; such stamps are called color changelings. Examples include sulfuretting (often misnamed "oxidation"), a reaction involving lead that may turn a blue or green stamp to black, and the effects of salt water, famously seen in stamps of New South Wales recovered from the wreck of the Colombo. Forgers have also used chemicals to try to produce seeming rarities, although by now experts know how to identify these attempts. Nomenclature In general, collectors follow the stamp catalogs in matters of color nomenclature, even though the different catalogs are not consistent with each other. Although there are a great many named colors, the selection used by philatelists is limited to several dozen, modified by adjectives such as "dark", "light", "pale", "bright" and "deep". In addition, two color names may be combined, as in "gray green" or "brown orange", where the first name indicates the direction of modification to the second color. Thus "brown orange" is a duller and darker orange, while "orange brown" has a tinge to it that is more orange than would be seen with a "yellow brown" or "red brown". This system becomes less clear when extended to other colors, and few collectors could describe precisely how "carmine rose" is different from "rose carmine". Certain colors such as "lake", a shade of red which often commands a price premium, have a traditional, but somewhat uncertain, meaning which differs from general usage of "lake" in terms of pigments and dyes. Originally, government-issued official descriptions merely gave out a primary name such as "red" for a whole range of shades. In more recent years, the descriptions have become more precise, such as "dark sage green",