You want to know what this piece is made of.
Test the metal. It is the only way to know.
"Would knowing the exact composition change what I do next?"
Do the magnet test. Examine color at edges. Feel the weight. These three observations tell you whether the piece is likely precious metal.
Start with a magnet. Examine edges for color change. Feel the weight. These tests are free, instant, and cause no damage. They rule out obvious fakes.
Only if prepared for a permanent mark. Use non-destructive methods or professional testing for pieces you want to keep unmarked.
It rules out iron with high accuracy. It cannot confirm gold content. Many non-magnetic metals resemble gold.
