Dear student,
Noble metal, any of several metallic chemical elements that have outstanding resistance to oxidation, even at high temperatures; the grouping is not strictly defined but usually include rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold.
Only Noble metals are used to make ornaments as they are having high resistance to corrosions. The other reason for this is that non - metals are non-reactive causing no reaction with other metals.
Regards