Gold Standard Meaning

(idiomatic) A test or measure of comparison that is considered ultimate or ideal.

Example: 2002, Philip Ball, The Elements: A Very Short Introduction, Oxford 2004, p. 57
  In countries that accepted the gold standard, currency could be exchanged at a bank for a fixed weight of gold.
  The OED is the gold standard for English dictionaries. Everyone wants to see how their version measures up to that ideal.