You will need
  • Gold
You can try to determine gold "by ear". Sound when falling on glass surface ring, the authenticity of which you are certain and check the ring should be the same.
You can also draw those and other jewelry a small line on any solid object. If both leave a similar footprint, there is a high probability that they both have the same sample.
Try using a magnet. Precious metals are not attracted. However, copper and aluminium, also not magnetic. In any case, is to estimate the weight, because aluminum and copper are much lighter than gold.
Apply to the surface of the gold drop of iodine for 3-5 minutes. Then gently wipe the liquid. If the color of the metal remains the same, you likely real gold.
Or try to hold the jewelry in vinegar. If it will darken, it is fake.