This necklace is magnificent.
I really think that for an evening it should be the most important thing in your outfit. For this you should wear a long dress, preferably black, dark blue or red.
Good luck!
Sorry but I guess you can't really tell that by one picture especially if you don't know the stones. If it is from the 1950s it probably has worth just because of the age. Maybe you should try to find out what stone it is or go to a jeweler, nonetheless it looks amazing and if you got it from a family member it should also have a big emotional value to you! ;)
Sorry if I couldn't really help but this one picture and the lack of information isn't just enough especially on this platform without the knowledge of a good, trustful jeweler!
This is such a good necklace for wearing it look good i think it estimate price is 1k dollar or more but this neklace is looking good and
new for wearing outside
It looks similar to the one on this site.
https://www.passionforthepastantiques.com/store/products/item/backPID/jewelry/products/blue-rhinestone-necklace-c-1950-1/?tt_products%5Bbegin_at%5D=180&cHash=2929a16c87d0c549fa36498f015ea74d
Since it's on a back date of 1950 it's worth will be about $800...since the stones still shine and will be just fit for a fashion show event putting on a milk colour dress..
Necklaces like this one where standards back in 50s. Almost every woman had one similar so i think there common things. Just for the age of it and the condition it is i would probably say that the cost will be around 25-35$. That's my opinion.
To me it looks as if it could be topaz or aquamarine. Its beautiful and in the condition its in considering the age the metal has to be precious. If i were to put a dollar amount i would say around the 5 to $6,000 range.