©Lin Yangchen

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In 1859, during the Second Italian War of Independence, the French army under the command of Napoléon Bonaparte scored a decisive victory against the Austrians in the Italian town of Magenta, near Milan. Hat-makers in Paris named one of their latest colours after it, according to the De La Rue Journal, and the name stuck. Napoléon also created the honorary title of Duke of Magenta (Duc de Magenta), which also became the name of a famous Thoroughbred racehorse in the United States.

When it comes to stamps, magenta has the distinction of being the colour of the world's most expensive stamp. But no stamp beats the 10¢ magenta coconut definitives for sheer diversity of shades. The varieties of the BMA MALAYA 10¢ and post-war 10¢ are legendary. But philatelists usually study these two issues separately, since BMA and the postwar Malay states are seen as different collecting specialties. Only when one views the whole panorama of the Universal Coconut Duty Plate from 1936 to the 1950s, including the pre-war Straits Settlements issues, does one see the full chromodiversity of the 10¢.

Foster Freeman VSC8000 philately
Examining 10¢ magenta shades with microspectrophotometry and hyperspectral imaging between 400 nm and 1000 nm.

The longer time scale of observation also lays the foundation for reconstructing a broader picture of the evolution of security printing doctrine and developments in ink manufacturing technology. I also embrace colour changelings in used stamps, an additional layer of variability usually excluded from colour studies, in the hope of uncovering insights into ink chemistry.

This is the first-ever full-colour photographic guide to the shades of the 10¢ coconut definitives. It catalogues both visible reflectance (left side of composite image) and ultraviolet fluorescence (right side of composite image) at high resolution and covers the complete lifespan of the coconut definitive. The aim is not to identify print requisitions or dates, which are in good hands, but to explore the colour spectrum of the 10¢. A calibrated and standardized imaging procedure ensures colour consistency and accuracy if viewed on a calibrated monitor. Note, however, that paper colour can influence the perceived shade of the ink.

brunei 1895 design precursor

Micrograph in cross-polarized reflected light showing a mixture of violet and salmon-orange pigment, slight bleeding of ink and birefringent cellulose fibres of different diameters.

pre-war straits settlements
(all non-fluorescent)


Aged Bordeaux.

Photomicrograph with a 20× plan apochromatic objective and transmitted Köhler illumination.

Kalamata olive.

Aside from being the imperial colour, purple is very interesting chemically and even biologically. For example, Tyrian purple (6,6-dibromoindigo) comes from the beautiful marine snail Murex. And one of the most exotic purple pigments is purple fluorite, which gets its colour from particular defects and impurities in the calcium fluoride crystal lattice. It is known to have been used only in southern Germany and the Tyrol from 1470 to 1520 (Spring 2000, Richter 2001). Modern violet pigments are often based on cobalt bonded to elements like lithium, magnesium and arsenic (Corbeil et al. 2002).

bma malaya

Cameron (1950) listed 11 printings of bma 10¢, while Murray Payne (2015d) lists eight. But Dr. Abdul Majid Dato Kassim’s tour de force shows 30 different combinations of shades, papers and dies, including subtleties like “purple-brown and light reddish purple”. Still, it was quite well-behaved when it started out in 1945.

Overprint on pre-war chalk-surfaced stock.

Brownish purple on post-war substitute paper.

Desaturated purples on wartime striated paper.

Aniline (phenylamine).

In 1947, all hell broke loose when magenta and fugitive inks became the rage. The inks were probably based on aniline, an aromatic amine distilled from coal tar. It smelt of rotten fish and was used as an ingredient in hypergolic rocket fuel at the time. Aniline-based stamp inks have been widely reported by philatelists to bleed through to the back of the paper and fluoresce like volcanic lava under ultraviolet bombardment.

Mauveine, derived from aniline, was the world's first synthetic dye, made by 18-year-old William Henry Perkin in London in 1856. In 1863, William De La Rue developed his own version, Azulin Purple (Young 2007). Its distinctive shade can be seen on the post-war 5¢ coconut definitives.

One of several forms of fuchsine, a magenta-coloured synthetic dye derived from aniline. Fuchsine is used in hair dye, artists' paints, microscopy and dermatology.

Alizarin is also a candidate dye, especially for the more reddish shades. It was used on British George V stamps. It can be pinkish or purplish depending on the accompanying fixative, and fluoresces like aniline. It is also used as a histological stain for calcium. It used to come from the roots of the madder plant but is usually synthesized nowadays. German and British chemists independently discovered the process at about the same time, but the Germans beat the British to the patent by one day.

Another pinkish dye with similar fluorescence is eosin, which is known to have been used for some Australian KGV 1d reds.

Phycoerythrobilin, which attaches to the biological photosynthetic protein phycoerythrin, gives a reddish colour. It has five-sided rings instead of the six-sided benzenes of the other pigments. A phytoplankton bloom involving this chromophore can give the water the shade of a 10¢ magenta.

Organic dyes seem much more variable in shade than inorganic pigments. Perhaps this is because every batch of dye is a different mix of many similar molecules with slightly different benzene ring configurations and substitutions (such as the above) and reflectance spectra, and manufacturing processes cannot or do not precisely control the composition. In contrast, inorganic pigments such as mercuric sulphide have a simple and (mostly) singular molecular formula, and the only significant degrees of freedom are their purity and concentration.

Hybrid form on substitute paper.

Chalky two-tone with differential fluorescence.

Full-blown chalky magenta.

The solvent in the cancellation was enough to make it bleed.

Photomicrograph with a 20× plan apochromatic objective and transmitted Köhler illumination.

post-war states

Historically, stamps printed with reddish inks were notoriously variable in shade (see Judge 2017, Hofmeyr 2020, Charles 2017 and Charles 2020a,b for examples from other parts of the world). In the case of De La Rue, it was not surprising, given that as many as six pigments were used to get the desired shade of magenta on a banknote (De La Rue c. 1950). For the coconut definitive, this was exacerbated by the fact that the post-war 10¢ had the largest production run of all the post-war denominations. Indeed, the first coconut stamp I ever saw in my life was a 10¢.

Stanway (2009) categorized them into early fluorescent and late non-fluorescent shades. The fluorescents were probably printed using ink recipes inherited from the late BMA issues. Non-fluorescent ink gradually took over and was in full use by the time of Queen Elizabeth II.

We thus see a macroevolution of coconut 10¢ shades from pre-war purples through the magenta craze to a refined and elegant post-war claret. Supply chains for ink constituents were probably disrupted during the war, forcing De La Rue to improvise, and stabilized again when peace returned. Canadian stamps got into a similar situation during World War I (Judge 2017).

Fluorescence spectrum (raw data) of a post-war magenta 10¢ on excitation with a 325 nm helium-cadmium ultraviolet laser through a 40× fused silica-calcium fluoride microscope objective.


‘Mint Never Hinged', ‘Very Fine Used' and other such decorations are highly coveted by stamp dealers and collectors. But there are the stamps that have endured half a century of hardship in the tropical heat and humidity. They have a rugged, uncosmetic beauty, like a sunburnt, dirty and sweaty Zhang Ziyi after the fight with the desert bandit in Crouching Tiger, Hidden Dragon.

Stanway (2009) mentions a Singapore 10¢ so unstable that the ink leaches out even in mint condition. Did the printer run out of fixative or forget to add it?


Photomicrograph with a 20× plan apochromatic objective and transmitted Köhler illumination.

One way to get claret-like shades was to mix ultramarine and carmine, as was done on the 1893 US stamps featuring the landing of Columbus printed by the American Bank Note Company (Brittain 2020). Claret did not always appeal to the authorities. In 1906, no sooner had the New Zealand commemorative featuring Maori art been printed in claret than the post office changed its mind, destroyed the stamps and reprinted them in vermilion (Glen Stephens; New Zealand Post).

I am grateful to Lim Kim Yong and Sow Chorng Haur (Department of Physics, National University of Singapore), Ernest Cheah (Nikon Imaging Centre, Singapore Bioimaging Consortium), and Poh Kian Hwee for valuable discussions and research facilities.


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