Amazing beautiful agate stone necklace! I'm not a gem expert but I believe the main stone is a Botswana agate as it is known for bluish grey and pink hues with fine banding. The darker stones are also a stone, likely another type of agate though the larger black beads are glass. The main chain measures approximately 20 inches. The main stone is 1 5/8" long and the entire pendant portion measures approximately 3 3/4" long. No chipping or cracks to the beads. Excellent quality!