You slide the shiny gold ring off your finger and there it is: that telltale green stain that says your new bling isn't quite so many karats as you thought.

That disappointment, with just a hint of betrayal, is what we're feeling about the Olympics right now. Like you, we read all the typical Olympic stories -- the triumphs, the heartbreaks and the heroes. Behind them, though, are darker stories of labour camps, child athletes and sweat shops.

They're the green stain beneath the Olympic gold. There are several stories that caught our eye and cast a pall over our enjoyment of these Olympic Games.

When the Games end, most returning Canadian athletes can look forward to a warm welcome and the love and support of their families and communities whether or not they have brought home a medal. North Korea's 56 Olympians are not so lucky.

According to former North Korean athletes who had defected and who spoke with an ABC news, those who fail to win in London, especially those who lose to archenemies like South Korea or the United States, face possible imprisonment and even torture in the secretive communist nation's brutal labour camps.

China's athletes may not face labour camps, but many are denied any freedom in their own lives. Chinese athletes say government officials seek out children as young as six who show potential. Whether they want to or not, the children are sent to sport schools where their entire lives are re-dedicated to athletic training. Other academic subjects are often left by the wayside, leaving the children with no other employable skills when their sporting careers are over. Visitors to these schools report seeing clear signs the children are physically abused.

During the 2008 Beijing Olympics, medal-winning Chinese canoeist Yang Wenjun told western reporters he had not seen his parents in three years. He said he had tried to quit sports many times, only to be threatened by Chinese officials.

And once again, it seems the polished pride of an Olympic host city comes all at the expense of compassion.

In East London the Clays Lane Estate, the U.K.'s largest housing cooperative, was demolished to make way for the Olympic athletes' village, depriving more than 500 vulnerable people of their homes. New laws gave London police more power to penalize the homeless "sleeping rough" in central London, shifting them to the margins.

It follows a pattern long-established in other Olympic cities -- Barcelona, Athens, Sydney, Beijing, and even Vancouver and Whistler -- to sweep their poor and homeless under the congested carpet of urban life to create a Potemkin-esque facade of civil perfection for the eyes of the world.

We found it a cruel irony that, even as British Government and International Olympic Committee (IOC) officials agreed to ban Syrian government officials from attending the Olympics for human rights abuses, official Olympic uniforms and merchandise fell under a human rights cloud.

Journalists discovered the plush toys of the Olympic mascots were manufactured in Chinese factories where workers were forced to work as much as 120 hours in overtime a month in unsafe conditions, for as little as $9 a day. Meanwhile British athletes were strolling about in their official uniforms manufactured by Indonesian factory workers toiling 65 hours a week for 53 cents an hour.

Make no mistake, those are sweat shops. We have seen more than a few, and we know the conditions that prevail within them. There's no excuse in this day and age for organizers of major events like the Olympics not to be aware of the issue and ensure their supply chains are ethically sourced.

The Olympic Games should stand for ideals higher than consumerism and national ego.

Pierre de Coubertin, founder of the modern Olympics, once said: "Olympism seeks to create a way of life based on the joy found in effort, the educational value of a good example and respect for universal fundamental ethical principles."

The job of the IOC is not simply to choose Olympic hosts and organize the Games, it also has a duty to uphold the high ideals Coubertin established over 100 years ago. There are positive signs the IOC is finally taking this duty seriously: for example, pressuring Saudi Arabia to allow women to compete. Reading the stories behind the stories from London, however, it's clear more effort is required from the IOC to take the tarnish off the Olympic gold.

Craig and Marc Kielburger co-founded Free The Children, and are authors of the new book Living Me to We: The Guide for Socially Conscious Canadians

Follow Craig and Marc Kielburger on Twitter: www.twitter.com/craigkielburger