O'Connor's men proving to be the jewel in European crown
Diamonds are that rarest of things -- a simple substance that is transformed by pressure and can cut through almost anything.
Based on this definition, Leinster are rightly shining at the moment; they pass and catch as well as any club side in the world, and this includes Dan Carter's Canterbury Crusaders and Quade Cooper's Queensland Reds.
Matt O'Connor's men are underlining the fact that well-timed and accurate passes can have big lumps chasing shadows.
And while they may not want me casting light on their dark arts, it is not all that complicated because their skills are based on doing a couple of basic things very well.
It sounds obvious, but watch this weekend's games and see how many sides fail to replicate them.
Leinster rugby players, and this is from one to 15, do their best to always carry the ball in two hands. This is crucial because it immediately provides options, making the defender stay honest.
When a ball-carrier has the ball in one hand -- tucked under his arm -- a defender can dive in, commit to the tackle and be in control of the contact.
Win or lose the contact, he can commit as he knows the ball-carrier has only one option, dictated by the one-arm carry.
This gives the defender power. Put the ball in two hands, and an attacker has the control. Like a snake charmer he can mesmerise, moving the ball back and forth, shifting body position and lines of running, luring in their prey.
The defender cannot make a decision early, they cannot set their feet early, cannot launch everything at the ball-carrier.
Should they dive in, then the attacker just moves the ball with two hands.
If their team-mates also have the ball in two hands, they can continue this chain of passing down the line until they either find some space or start coming back the other way, probing, the ball kept alive, the game moving, the pressure building, gaps increasing, defences being stretched.
Eventually, a defender will panic and take the wrong option, diving out of the line or drifting on to the next runner anticipating an early pass. But while two hands are crucial to this, they are used as a formative structure based on the Canterbury Crusaders' diamond.
The tip of the diamond is the ball-carrier. They then have support on either side, with a runner tucked in behind to complete the diamond shape and provide options. There is no point having the ball in two hands if there are no support runners and Leinster's players have evolved to the level that they are rarely left isolated.
This is down to a stability and quality of selection, which breeds confidence in the ball-carrier, helps stoke a desire to go out and score tries, and allows the boys in blue to trust that people will be there.
Keeping the ball in two hands also allows them to keep their shoulders square when running with the ball and, when coupled with their urge to get wide early, it significantly increases their options.
Most players are a bit lazy getting around the corner and this limits them to crabbing sideways, giving an easy side-on angle to the tackler.
Race around the corner, work crazy hard and you can earn some extra yards, run straighter and keep your shoulders straight.
Stay square with the shoulders as an attacker and you can move the ball into space or away from the defender, exploiting space on whichever side it appears. These are simple skills and yet they are often forgotten as teams overcomplicate.
The power of simplicity should not be underestimated. You only need to look at how Connacht performed last week to see what can happen when you focus on the basics: heart, guts, and determination.
Before last week's game, Connacht were bottom of the Pro12 and coach Pat Lam was only just finishing off his apology after his side were badly mauled by Edinburgh -- they were dreadful.
The Scots are not exactly a European heavyweight and Lam was lamenting an "unacceptable display".
After a rollicking you often get a reaction, but no one could have imagined it would be against the French aristocracy, especially when they were playing at Stade Ernest-Wallon, where only a few of the very best win.
Connacht showed what is possible when you are prepared to commit your heart and soul to an effort -- it was a staggering display of courage and willpower to deny Toulouse in their own back yard.
Search your history books for sporting upsets on this scale; there are very few.
Robbie Henshaw, Kieran Marmion, John Muldoon -- those names will probably be talked of in Galway half a century from now and the effort Connacht put in should be an inspiration to many sides this week in the Heineken Cup.
When all seems lost on a field, when team sheets don't stack up, when history says you can't win, then stick the name of Connacht up on your wall and remember what can be done.
Toulon will look to batter Exeter and take the bonus point in the south of France and set themselves up for a chance of retaining their title.
Clermont must take their stellar names to Scarlets and kill off a group that was brought back to life by Quins' win against Racing Metro in Nantes.
Munster go to Perpignan, the site of one of their greatest backs-to-the-wall wins, knowing full well that Gloucester's victory at Edinburgh has the boys from the Shed breathing down their neck.
Toulouse will be heading to the west of Ireland with a chance to avenge their loss and make sure that they set down a marker ahead of Saracens' visit in the next round.
Ulster are looking to take the heat out of round six and a trip to Welford Road with a good win against Treviso in Italy.
There are various complications and permutations that could arise this weekend and the pressure is building. Now it's time to see which teams can turn themselves into diamonds; rough or polished.
(© Daily Telegraph, London)