Each hair follicle contains a certain number of pigment cells. These pigment cells continuously produce a chemical called melanin, the thing that makes our skin colour also give us our hair colour. The darker the hair, the higher the melanin count.
As we get older, the pigment cells in our hair follicles gradually die. When there are fewer pigment cells in a hair follicle, that strand of hair will no longer contain as much melanin and will become a more transparent colour.
When does your hair go grey?
People can get grey hair at any age. Some people go grey at a young age -- as early as when they are in high school or college -- whereas others may be in their 30s or 40s before they see that first grey hair. How early we get grey hair is determined by our genes. If you need a bit of an indication, look to Mom and Dad.
When we think of grey hair, we think of grannies and the elderly. We have guests come to see us who have been seeing the silver strands pop through at 24. It has a huge effect on women and men. Used to seeing nan and granda as silver haired, suddenly, they feel old.
Can you prevent your hair from going grey?
As we said, it's down to your genes. There have been a lot of studies done on if grey hair is increased with stress, but its genetic; just like you are tall or short, you can't control it.
Is grey hair so bad?
Honestly, I love grey hair. Billie Crago is our colour specialist in London Hair Salon and openly thinks grey hair is cool on men and women. We love when we see female actors embracing their greys as they age. It's not an indication that you are old, as with the right hair cut, it can look super suave and chic. Men have it a little easier, as it tends to make them look distinguished.
I've just gone grey, how can I look after it?
As you lose the melanin, you might find a change in texture in your hair. The products you once swore by no longer work for you. Time to get in to a salon and see a stylist for a consult. We recommend the Age Premium range from Kerastase.
Celebs that wear it proudly
Sarah Harris is a fashion editor for Vogue who started to go grey at 16, and instead of shelling out hours and hours at the salon to change her appearance, she has embraced her silver locks. Its come to be her trademark.
Jamie Lee Curtis stopped dying her hair nearly 10 years ago. Her sharp cut makes her look youthful.
Country legend Emmylou Harris looks amazing grey.
Celebs that want to be a part of the Grey Gang
Nicole Richie went white to the met ball.
Marina and the diamonds is possibly wearing a wig here, but it still looks cool.
Kelly Osbourne has been rocking shades of grey for a while