It seems the design for clasp to be from the 50's period however guilloché is used for a large period, however it can be a bit younger, not sure, best would be to study the style, but it seems already in the 60's the design are closer to mikimoto, oval with cup shape and pearl in middle, or even more modern shape.
The earlier shapes look like the typical octagon or hexagon with diamonds, white gold, and earlier seem to be the barrel shape.
This kind of shape, like mine, coult even be far older, but the pearls, especially color and quality are not that old in my opinion, making me think about the 50's, also graduation is soft.
Lenght is quite long, 55cm
Gold is rose gold.
I has been restrung by the previous owner in 2005 and never used or so, only kept, and I watch it from time to time.
So I will leave as it is, even the restrung is not the best, quite loose.
it has been worn once by a friend for a picture.
I measured the pearls, smallest are 5,5 and largest looks like over 8,5mm.
I have to buy new battery for my caliper, it was flat.
I am looking for older period, before WWII, I found one, about 1900 period, but still in shipment process.
I bought a nice brooch with natural pearls, tested for gold (18ct) and probably platinum on front.
The brooch is art deco, with pearls and rose cut diamonds.
It makes my third jewel with pearl theme, first is the necklace and second is a tie pin.
about old, you are right, no way to get sure, only get sure about old clasp, or genuine period clasp especially for british hallmarks, french hallmarks are much more difficult, eagle head is used since 1838...
