Ruby Birthstone Diamond Ring 10K White Gold | Mullen Jewelers10k white gold diamond and ruby birthstone ring. The perfect July birthstone ring or mothers ring, this 10 karat white gold band has round red rubies and diamonds alternating half way around the ring. All birthstone rings and mother's rings are available in all birthstones, although the April (diamond) version may cost more. Looks great worn alone, or as a stackable ring.