Hello everybody,
As a new member, I am replying a bit late, needing time to browse all forum...

Well ,have you ever heard about changeable clasps? I am using them. It is a Swisss registered mecanism that allows safely to open and close -of course- plus changing clasps and fitted necklace as well. It is composed of 2 special steel or gold keys to be drilled and fixed at the 2 ends' necklace (then easily re-string the pearl necklace).
Then the clasp is a " push and turn" system that safely goes into the necklace's keys. The clasp itself is a steel or gold mecanism that can be easily set into a pearl or a bead stone or all in steel or gold as well. So you can use one from your pearl necklace to convert it into a clasp and make a pearl necklace + clasp with the strand.

Moreover the interest is to change from on another :either changing the clasp either changing te necklace.

Australian and German people are very found of that system.
See my site for more info. Don't hesitate if more infos needed at changezdefermoir@myway.com.

Hope it can helps !!