Graphite is a stable alloy with no detailed specifications on what it's melting or boiling point is. Graphite can withstand up to 5000 degrees Celsius of constant pressure. You can place your gold or silver into a graphite crucible, heat it in a furnace and obtain molten magma with no worries that the heat applied will leave a dent on your graphite crucible. Note that while graphite does not possess a specific melting point, graphite crucibles are prone to break when exposed to a temperature beyond 5000 degrees Celsius.