The celtic knot is an ancient symbol of the journey of life. With no beginning and no end, the knot represents the timeless nature of our spirits and the world we live in. A Lab Ruby celtic knot combines these concepts with the spiritual attributes of the Lab Ruby . Ruby is known as the gem of courage. Wearing a ruby pendant can help you get through the trials and tribulations of life. A perfect stone for nighttime wear, a black onyx pendant looks elegant and stylish in white or yellow gold.