I also did some reading on Suffragette Jewelry. Interesting indeed. It seems though that the idea that the colors represent the slogan is a myth, though. The slogan that was used was different, and this idea may have been added to the jewelry colors after the suffragette period.

Also, a necklace from the 1920's being suffragette jewelry would surprise me. The period in which suffragettes were most active was before WWI, with (partial) voting rights for women in the UK being awarded in 1918. It seems that suffragette jewelry was mostly delicate pins between 1908 and 1914 with gemstones, pearls and enamel.

Stefany, I would be interested to know if, except for the color scheme, there is anything else that points this necklace towards suffragette jewelry.