Black â€“ the color of night, the color of elegance. Whether itâ€™s that little black dress thatâ€™s just perfect for any occasion, or a pair of black onyx earrings that go with everything â€“ you canâ€™t go wrong with black. Black onyx is the mystical birthstone of December, and a black onyx ring or a black onyx pendant makes a perfect birthday gift. Black onyx is a perfect gem for a custom keepsake ring or pendant. Mix it with any other gem â€“ it goes with everything. Perfect for every day or that special occasion, onyx jewelry is a versatile and elegant choice.