This replacement screw-on synthetic opal shines in a 14k gold setting. Synthetic opals are more intensely beautiful and colorful than authentic opals, and are considerably more durable. Internally threaded, this replacement opal ball will screw-on to any barbell. These replacement balls are specific to FreshTrends custom gold body jewelry – select 14G for body jewelry that is 14G and select 16G for body jewelry that is 18G to 16G.