How to Check If My Gold Is Real and What It’s Worth?

Hi! I just bought a gold jewelry online and now I’m curious — is it really 18k gold? And how much is it actually worth?

This is my first time owning gold. I got it as a birthday gift to myself and I’m thinking maybe this could be the start of a little gold investing.

Any tips on how to check if it’s real and what its value might be?