This Brilliant Tennis Necklace features 4mm round cut cubic zirconia. Each CRISLU flawless and exquisitely cut cubic zirconia stone is handset in precious .925 sterling silver and finished in 18kt yellow gold for a total diamond equivalent weight starting at 23.35 ctw for the 16", and up to 37.50 ctw for the 24". CRISLU jewelry is 100% hypoallergenic.