Pearl Necklace from Chr. Timmerberg Bremen Germany, what is it worth

by Margaret
(Petersburg)

I am trying to find the value of a pearl necklace for my friend. The necklace belonged to her mother. My friend is in her late 80's so the necklace could be much older than her. She wants to sell the necklace. Can you assist with its value and maybe a way to determine the quality and if the necklace is real pearls or what they are.