Thanks for your suggestions, whenever I have the courage to drill the pearls in an angle, I'll show you the result.
By the way, I saw a necklace like that in a very old film, dating from the time they didn't have round freshwaterpearls yet, so it's a definite case of miscasting, the actress must have been wearing fake pearls.
Later, surfing the web, I found it on a pearl site but I don't remember which one
Marjan (dutchpearl)