Sapphire Channel Set Birthstone Ring 10K White Gold10k white gold sapphire channel set birthstone ring. The perfect September birthstone ring or mothers ring, this 10 karat white gold band has channel set round sapphires going 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. Finger Size 7.