I don't doubt it's gold since there's no reason why one would gild a silver or bronze one - these are IMO quite personal awards that generally would be left alone in their boxes, only to be looked at on occasion, and are generally sold only after the original owner has passed, since their sentimental value is far greater than their monetary value.
The main use of these today is in academia - gold for the top graduating graduate student (MA/PhD, etc.) at a univ, silver for top undergrad at a college/univ, and bronze for top graduate at a secondary school or trades school.