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 Emerald celtic knot combines these concepts with the spiritual attributes of the Lab Emerald . The birthstone of May, an emerald ring symbolizes the eternally returning spring. The velvety green color of emerald is a perfect match for spring and summer fashions. The birthstone of December, the tranquil azure color of a blue topaz ring can evoke thoughts of warm Caribbean seas on a cold winter day.