The quality of diamonds are measured by cut, colour, clarity and carat. Photo / iStock
The quality of diamonds are measured by cut, colour, clarity and carat. Photo / iStock
Why are diamonds so expensive?
Up until late in the 1800s, diamonds were considered very rare, so were valued highly.
But then prospectors found a large crater of the gemstones in South Africa which worried the De Beers Mining Company.
So they banded the mining corporations together to control thevast majority of the diamond stock and agreed to release diamonds only in small batches.
Today the rough diamond supply sector has many more businesses competing within it, and De Beers Group has a much smaller share of global rough diamond supply, around 25 per cent by volume.
Currently, not only are diamonds rare, they are getting rarer every day.
The quality of a diamond is determined by the four Cs: cut, colour, clarity and carat.
Some of the most expensive diamonds in the world are The Cullian (US$400m) which is 3,106,75 carats, the pale yellow Sancy Diamond which is priceless and the infamous Koh-I-Noor which is also unvalued and was once the largest cut diamond in the world.
What's behind my belly button?
Whether you're an inny or an outy, the answer's the same - nothing useful (unless you need surgery or to find your core for balancing).
The second the umbilical cord is cut after a baby is born, it stops serving its purpose. All that's left is its shrivelled remains which is now scar tissue.
For the nine months that a baby is in the womb, the umbilical cord is its lifeline that carries oxygen-filled blood and nutrients from its mother's uterine wall and carries the foetus' waste away.
It grows as the baby grows and usually reaches up to 50-70cm in length - though this is sometimes longer if the baby is more active and needs some extra length to move around.
The only time your belly button might be once again useful is if you need laparoscopic surgery and it serves as an entry point to your abdomen that won't leave a scar.
It's also used by yoga teachers to encourage people to find their centre of gravity by activating their core.
Why is it called a black box if it's orange?
For starters, it's not called a 'black box' by anyone in the industry but goes by its proper name: Flight Data Recorder.
And it does exactly that - records all the flight data like the engine exhaust, temperature, fuel flow, aircraft velocity and altitude.
It also records the pilots' conversation, but the tape is only two hours long so it has to loop.
A writer for a Dutch airline once heard of a pilot who'd say 'I love you' to his wife every two hours because of this looping and just in case something went wrong.
But why, then, does the layman call it a black box? There are a few theories.
One, that it used to be painted black to prevent reflection when it was first invented by the Australian scientist David Warren in 1957.
Another theory is that 'black box' is a generic science name for devices with complex internal workings.
A plane's black box is actually an orange cylinder. Photo / stock
Why do we use mint to clean our teeth?
When toothpaste was first invented in the early 1900s with the advent of Pepsodent, its creators put mint extract in as a savvy trick.
Mint, and a few other ingredients, are irritants so make your gums and tongue tingle which makes you think the toothpaste is working - even though it has nothing to do with its efficacy.
Menthol also stays in your mouth for a while, prolonging the 'clean' sensation.
And now we just associate minty with being 'minty fresh'.
Mint is also a Western taste. In India, they like spices like fennel, amla, neem or clove while in China tea flavours, floral flavours and Jasmine are preferred.
Toothpaste companies have launched other flavours, like cinnamon and baking soda, but they've never taken off like mint.
Why is yawning so contagious?
About half of adults yawn when someone else does - and scientists aren't 100 per cent sure why.
In fact, we still don't really know why yawn at all.
Scientists don't really know why yawning is so contagious. Photo / stock
Some of the theories are that when we're tired we stop taking deep breaths which causes a build-up of carbon dioxide in the bod, that it cools the brain or stretches the body and organs.
