Etched preform tip

A container formed from a preform by stretch blow molding, the container comprising:

• a finish at a first end of the container, the finish configured to cooperate with a closure to close the container;
• a base at a second end of the container that is opposite to the first end, the base including a center push-up portion at an axial center of the base, a heel at an outer periphery of the base, and a flexible diaphragm between the center push-up portion and the heel;
• a body between the finish and the base;
• and
• an etched portion at the flexible diaphragm of the base, etching of the etched portion is a visual indicator configured to show whether the base is accurately blow molded or not accurately blow molded, the etching is confined to the flexible diaphragm and is configured to make the flexible diaphragm relatively lighter than each of the center push-up portion and the heel to make the flexible diaphragm relatively more flexible than each of the center push-up portion and the heel;
• wherein:
• when the etching is at a predetermined location of the base, the base is accurately blow molded;
• when the etching is not at the predetermined location of the base, the base is not accurately blow molded;
• and
• the etching is at only one of an outer surface and an inner surface of the base.