Da Vinci Code, The Easter Egg - Harry Potter Reference

That isn't a reference to Harry Potter. Nicholas Flamel was a real person born in 1330, who studied alchemy and is said to have actually been able to make silver and gold. Look him up.

ya harry potter was referencing to the priory of sion

According to what I have heard, Echizen_Kurage is right Harry Potter and the Sorcer's Stone is the title of the American version of the first Harry Potter book/movie, everywhere else, it's called Harry Potter and the Philosopher's Stone, the Philosopher's Stone (as it is properly called) was made/found by Nicholas Flamel, in Harry Potter, the stone can be used to make you immortal/invincible (the reason why Lord Voldemort wanted it), and can turn anybody you touch to dust (this is how Harry Potter turns Professor Quirell/Voldemort into dust at the end of the movie) In real life, Nicholas Flamel made/found the Philosophers stone, but instead of the stone having powers to make you immortal and turn people to dust, it has the power to turn any metal to gold and probably silver I am not sure how factual this information is, but based on what I have heard, this seems to make sense

Hey the priory of sion is a hoax. Nicolas Flamel really existed though. I believe both opinions are correct, his name was used by both rowllings and brown in a fairly correct way.