These are 15 of the rarest colours on Earth – and where they come from

Scientists estimate that the human eye can distinguish up to 10 million colours. That’s pretty impressive, considering the interesting fact that we only have three types of colour-perceiving rods in our retinas: red, green and blue. But when you think about all the different shades and tones in each colour category, what sounds like a weird fact at first begins to make more sense. The seven best-known hues of all, of course, are the colours of the rainbow. Red, orange, yellow, green, blue, indigo and violet have been commonly known as ROYGBIV for years, an unwavering rainbow fact. But with 9,999,993 other colours out there just waiting to be seen, we thought it was time to investigate rare colours around the world.

We’ve rounded up the coolest and rarest colours, from killer pigments (literally) to science-fiction shades that could leave your zodiac power colour in the dust. There are colours you can only see in ancient art, some accidentally invented in the lab and colours you shouldn’t have in your bedroom – at least if you ever intend to share it.

This gorgeous blue paint shade was once such a rare colour, the cost often exceeded the price of gold. Artists would wait for months for shipments to come in. The pigment was made from grinding lapis lazuli, a gem found mostly in Afghanistan. Its rarity meant that it was used very sparingly, and it was usually reserved for extremely special uses, such as painting the cloak of the Virgin Mary in religious artworks. In the late 1820s, synthetic ultramarine began to be manufactured in France and Germany, replacing the expensive and labour-intensive process of mining, shipping and grinding up lapis lazuli.

Kermes red is the oldest known red dye, and it dates back to the early Egyptians. It’s made from grinding up the dried bodies of bugs – in this case, female kermes insects, which live on the kermes oak tree. This stuff was once so valuable that a landlord in the Middle Ages accepted kermes dye for rent payments.

Kermes red was a rare colour because it took hundreds and hundreds of insects to make a strong colour. It fell out of fashion when the cochineal insect (native to Mexico) was discovered by Europeans. The cochineal was more strongly pigmented, so the red colour took fewer dead bugs to make. Kermes red has mostly been replaced by synthetic dyes, but you can still find cochineal insects in cosmetics and lollies.

This is the rarest purple colour, and it has an amazing myth go to with it: The demigod Hercules was on his way to visit a sea nymph when his dog started chewing on something on the beach. When Hercules finally got his pooch to drop it, his snout was stained a beautiful purple – and the nymph asked for an outfit in the very same colour.

The mythical pup was chomping on a spiny murex sea snail, which produces the purple colour. And because the beach was by the ancient Phoenician city of Tyre, the name Tyrian purple came about. It’s apparently the stinkiest dye in the world, and the challenges of getting the dye from the snail make it one of the rarest colours. This led to purple becoming a colour associated with royalty.

Now let’s check out some royal pets!

This soft-yet-vivid yellow is considered a rare colour because of its exceptionally bizarre origin. Used by artists including Van Gogh, Indian yellow is said to have come from the urine of undernourished cows in the Bengalese city of Munger. They were fed nothing but mango leaves, so their waste gave a brilliant yellow pigment that was in great demand by artists.

After an investigation in 1883, the Royal Society for the Encouragement of Arts published a report with eye-witness testimony of the terrible treatment of the cows. It took another 25 years for the practice to be banned entirely. We can still see Indian yellow today at one of the most popular museums in the world: the Museum of Modern Art in New York. The bright yellow stars in Starry Night by Vincent Van Gough were painted with it.

Also called Egyptian brown, this rare colour has a pretty gross story behind it. The pigment was produced by harvesting mummies and grinding up their flesh to produce a sludgy brown colour. This wasn’t just in the ancient past, either. Mummy brown was available from the 16th century until the 1960s. As you would expect, supplies of real mummies dwindled significantly, and there were rumours that more recent bodies were used to create the pigment.

Mummy brown fell out of fashion as times changed and is definitely one of the paint colours to avoid in your home.

Quercitron yellow takes the crown as the most forgotten colour. This is partly due to its two confusing names – what we now know as quercitron yellow used to be known simply as quercitron or more commonly as “Dutch Pink.” Umm, what?

Apparently, in the 18th century, the word pink referred to a yellow colour, and no one is exactly sure why. Dutch pink was made from either Persian berries (also called buckthorn berries), which are native to the Mediterranean, or from the yellow inner bark of the American black oak tree. This lovely yellow dye fell out of favour as synthetic dyes began to take hold in the mid-19th century.

Warm white can look dingy in some lighting – it’s one of the paint colours that can make your home look dirty. But what about something cooler or more opaque? We wouldn’t recommend this one. One of the most important colours in art, lead white is one of the rarest colours in modern times. But if it was good enough for the ancient Egyptians, Greeks and Romans, why isn’t it good enough for us? Well, we know something they didn’t. While ground-up lead carbonate might be a gorgeous, brilliant white shade that’s perfect for extending the life of your oil paints, it can also cause lead poisoning. Lead white was prized because it is such an opaque white. The density of the paint allowed artists to paint brushstrokes of light into their work, bringing the paintings to life in a new way.

We can credit the current houseplant craze to Millennials, but it was the Victorians that started the indoor plants trend. The preferred hue of those green-thumbed sirs and madams? Scheele’s green. This springtime hue echoed meadows of grasses and lush gardens. The only problem was that it contained arsenic.

This rare colour was a killer, poisoning artificial flower makers (often young women) as they dyed cloth green for leaves to adorn the hats and coats of the wealthy. Green was the most fashionable colour of the time, and you couldn’t have green without arsenic. It was in wallpaper, clothes and even food and beverages. Green colours today are made without arsenic, but often contain chlorine – safer for our bodies, but sadly not for the planet as it can’t be recycled or composted.

This hue doesn’t make the list of rarest colours because it’s from actual dragons. The bright red pigment is actually a resin from the bark of rattan palms or trees in the Dracaena genus, which grow in Malaysia, Indonesia and Yemen. Dragon’s blood red was used by the Romans as a red dye and by ancient artists as paint, although by the 19th century, the consensus was that this astringent resin was better as a varnish than a painting pigment. Today, it is still used to varnish violins. If you see red paint on the ground, it could be dragon’s blood – or maybe there’s a violin-maker nearby.