I dont see the telltale collar on yours. My girl has the yellow legs and the gold neck collar. They can also have grey neck collarsNo idea about what Sapphire Gems are blended with, but here are a couple articles:
http://www.edelras.nl/chickengenetics/mutations2.html#gen_mut_leg
https://articles.extension.org/page...or-small-and-backyard-flocks:-an-introduction