Interested in melting gold or silver and casting ring settings or 3D pendants
I'm afraid bold and silver both have melting temperatures that are too high for silicone molds to withstand.
There are several types of RTV silicone rubbers that you can use for casting low-temperature metal/alloys like tin and pewter (SmoothOn's Mold Max 60 has the highest heat resistance that I know of at 560° F / 294° C), but RTV silicone is NOT recommended for higher melting temperature metals.
To cast in gold and silver, you'll need to do lost wax casting. Here are two instructables and an online example that go over the lost wax casting process:
Hope this was helpful!