Why do we say 'going green with envy'? They say that jealousy is the green-eyed monster. This is because jealousy can lead even the nicest people to do awful things! It has a reputation for ruining important relationships. No one knows who first came up with the term 'green-eyed monster' or when it was first used. The phrase was used, and probably coined, by William Shakespeare to denote jealousy in his written work, The Merchant of Venice, in 1596. Some believe that green has been linked with jealousy since the ancient times. Greeks believed that jealousy occurred as a result of the overproduction of bile, turning the skin slightly green!

The association between colour and emotion is well known. Ever wondered why we say we are 'feeling blue' when we are depressed or sad? Studies have shown that intuitive metaphors like feeling 'blue' have their roots in reality. Dark, muted colours tend to be associated with gloom and sadness, while bright colours are perceived as happy. It is also an expression that describes the customary practice among several old deep-water ships. If a ship lost a captain during a voyage, it would fly a blue flag and have a blue band painted along the entire hull when returning to its homeport.

The first colour that comes to mind when you hear 'Sapphire' is blue. The different trace combinations of iron and titanium lend the different shades of blue to the gemstone. There also is a rare and highly valuable sapphire, which appears blue to violet in daylight and changes to purplish red or purplish blue when lit by incandescent light. Isn't that fascinating? To add to their enigma, blue sapphires are considered to have healing properties. They are believed to be the talismans of authority, truth and protection. This gemstone is used to celebrate 45th and 70th wedding anniversaries in the Western culture.

Aquamarine is a bluish-green member of the beryl family that symbolizes hope and is believed to bring good health. It gets its name from Latin words that mean water and sea. It is also used to protect sailors, assuring a safe voyage and preventing seasickness. According to a legend from the Middle Ages, if a man hid a piece of Aquamarine inside his mouth, he could call the devil and force him to give a truthful answer to any question. It is said that as long as the man kept the stone in his mouth, the devil could neither harm nor deceive him!

Prasinohaema skinks living on the island of New Guinea actually have green bones and tissues. Their blood is green too and is a deadly poison. They have an incredibly high concentration of the bile pigment, biliverdin, which makes their blood green. No other vertebrate is known to have green blood. What makes it further interesting is the fact that biliverdin is extremely toxic and if humans have even a tiny amount of biliverdin in their blood, it means that they are suffering from jaundice. It is surprising because at these concentrations of bile pigments in the blood, skinks should be suffering from jaundice too!

Located in the jungles of Columbia is Cano Cristales, which is known as 'The River of Five Colours'. It makes for a pretty picture with pink, green, orange, red and yellow mosses and plants growing under cool, crystal-clear waters. It is considered to be the most beautiful and colourful river in the world. When the water level is perfect, one can see different varieties of algae and moss in full bloom, flaunting an array of colours. Macarenia clavigera, an interesting species of plant that lines the river floor, turns brilliant red like autumn leaves; though this happens for a brief period, it is a sight to behold!