Hand Blown Caged Cobalt Blue Bubble Glass Metal Footed Vase.

Hand Blown Caged Cobalt Blue Bubble Glass Metal Footed Vase. Approximately 14 1/2 inches height 25 1/2 inches circumference at widest point Top & base 6 inches diameter  The top of vase approximately 1/4” down has what appears to be an internal crack however cannot be felt from either side and does not start at the top of glass. I am assuming this is a manufactured defect? It is also not visible with normal display and only when light is shined through it. Please view pictures for details.