Proverbial Meaning: Appearances can deceive you.
Literal Origins: Things that appear shiny or to sparkle are not always as worthy as they seem. Comparisons can be made between brass and gold, as brass appears to be gold in colour but its worth is far less. Fool’s gold (pyrite) is often associated with this proverb, which warns of deals and opportunities that seem too good to be true.
Common Usage: This is a very well known proverb, not spoken too often but usually quoted literally as a warning when it is.