A pearl, peridote and pink tourmaline necklace. Circa 1900.

Might be a Suffragette piece.
Suffragettes were members of women's organization (right to vote) movements in the late 19th and 20th century, particularly in the United Kingdom and United States. Suffragist is a more general term for members of suffrage movements, whether radical or conservative, male or female.In 1909 the WSPU presented specially commissioned pieces of jewellery to leading suffragettes Emmeline Pankhurst and Louise Eates. Some Arts and Crafts jewellery of the period incorporated the colours purple, white and green using enamel and semi-precious stones such as amethysts, pearls, and peridots. However jewellery that incorporated these stones was already quite common in women's jewellery during the late 19th century, before 1903 and could not be connected with the suffragettes, before the WSPU adopted the colours. Also, it is a popular myth that the colours were green, white, and violet, in order to spell GWV as an acronym for "Give Women Votes".