Red-green and yellow-blue are the so-called "forbidden colors." Composed of pairs of hues whose light frequencies automatically cancel each other out in the human eye, they're supposed to be impossible to see simultaneously.
Overall, the blue color scheme was perceived as most trustworthy and black as least trustworthy.
"Red and green should never be seen without a colour in between," goes the old saying.
The rare colour is termed 'True Cyan'. An optical illusion that has got everybody hooked features a “never seen before” shade of Cyan appearing on the screen. The rare colour termed 'True Cyan' largely escapes the human eye due to the fact that it is extremely difficult for electronic devices to produce them.
Whether it's navy blue, mid blue or even light blue, green really goes well together with it because green is a little warmer. Blue is a cooler tone, green is a warmer tone and together they harmonize and work perfectly.
In many cultures, black is thought to be unlucky and black cats, in particular, are said to bring bad luck to anyone that crosses their path. In China, white is generally seen as unlucky, while Brazil and Thailand consider purple to be a colour that can bring about misfortune to anyone who uses it outside of a funeral.
Lead paint was banned by most countries, but some homes built before the ban still have dangerous lead paint. Other harmful colors include fluorescent radium green, arsenic green, and uranium orange.
Complementary colors are simply colors that are directly opposite each other on the color wheel. Rather than complimenting each other (as people often think), they cancel each other out; a mixture of them would produce a greyscale color. Classic examples include red and green, blue and orange, and yellow and purple.
For example purple and yellow are opposite each other, as are blue and orange. These combinations are what people often call a colour clash, as they are bright, but they DO go together and create a great scheme.
Red and green cancel each other as do yellow and blue. They further reasoned that if one started with a color such as bluish green it should be possible to mix this color with a unique yellow to cancel out the blue content leaving only green. This is the basic idea behind the hue cancellation technique.
Other names the color was called were Paris Green and Emerald Green. So why was this color so poisonous? In case you didn't pick up what the key ingredient was – Scheele's green was loaded with copper arsenite, one of the deadliest elements to have ever been discovered.
THe most important of these is the range of yellow, orange and red pigments based on cadmium, which is a toxic heavy metal and is regarded by the California regulators as a possible carcinogen.
Black – Western World
Wearing dark colours for mourning has long been a tradition in many parts of the western world, in particular large parts of Europe and North America. The association of the colour black with death and loss is centuries old and is believed to have originated during Roman times.
In many parts of the world, black is traditionally the color of death, mourning and funeral fashion, but it is not the universal color of mourning everywhere.
According to the study, white cars are 12 percent less likely to get into an accident than black cars are, regardless of the time of day. Cream, yellow, and beige cars also ranked closely behind white; yellow actually surpassed white as the safest color in some studies as well.
Lucky colours: Green (especially light green), silver, creamy yellow and grey are good.
Gold. According to Feng Shui principles, the colour gold can help manifest good luck and it also plays an important role in attracting money.
That's because red symbolizes fire, and it is thought to bring good luck and good fortune.
Overall, navy color pairings should be clear, crisp, and bright. Black-shaded hues like dusty purple, hunter green, and maroon share navy's intensity and are likely to fade when paired with the dark-blue hue.
However, the old sartorial rule that cautioned against wearing black and blue together (especially dark blue or navy) has no real merit. The truth is, most neutrals look great together, like white and beige, black and white, white and navy … You get the idea.
Aconitum napellus (Monkshood): A Purple Poison.