Cal. Bus. & Prof. Code § 22125

If a quality mark is applied to an article in accordance with the provisions of subdivision (e) of Section 22128, it shall not apply to pin tongues, joints, catches, lapel button backs and posts to which they are attached, scarf-pin stems, hat-pin sockets, shirt-stud backs, vest-button backs and any screw backs, if such parts are made of the same quality of gold as that used in the balance of the article.