Gold’s melting point is a definition, not just a measurement
Most physical constants are measured and then refined as instruments improve. The freezing points of gold and silver are different: they are defining fixed points of the International Temperature Scale of 1990, known as ITS-90. Laboratories calibrate thermometers by melting and freezing very pure samples of these metals, and the scale assigns gold 1,337.33 K and silver 1,234.93 K. In Celsius that is 1,064.18 °C and 961.78 °C, obtained by subtracting exactly 273.15.
Copper, aluminium, zinc and tin are fixed points of the same scale, which is why their figures here also carry three decimals that a materials handbook would normally round. Platinum and palladium are not ITS-90 fixed points; their values, 1,768.2 °C and 1,554.8 °C, come from the CRC Handbook of Chemistry and Physics, and the table says which source each row uses.
Why karat gold has no single melting point
A pure metal melts at one temperature. An alloy melts across a range: it begins to soften at a lower temperature called the solidus and becomes completely liquid at a higher one called the liquidus. Both depend on exactly what is in the alloy. Two 18K golds — one yellow, alloyed mostly with silver and copper, and one white, alloyed with palladium — do not share a melting range, even though both are 75% gold.
That is why this page has no row for 9K, 14K, 18K or sterling silver. Published figures for those do exist, but each one describes a particular manufacturer’s alloy. Presenting one as the melting point of all 14K gold would be precisely the false precision this site avoids. What can be said with certainty is the direction: adding copper, silver or zinc to gold lowers the temperature at which it starts to melt, which is part of why karat golds are easier to cast and solder than pure gold.
What the numbers mean at a workbench
Solder works because of these differences. A jeweller’s gold solder is an alloy designed to melt below the piece it joins, so a seam can flow without the whole ring slumping. The same logic explains why repairs on platinum need different equipment: platinum melts more than 700 °C above gold, so platinum work calls for different equipment and technique.
The temperature check above is for orientation, not instruction. It tells you which pure metals would be liquid at a given setting. Real casting temperatures sit above the alloy’s liquidus by a margin that depends on the alloy and the mould, and that is the alloy supplier’s figure to give rather than a number to derive here.
Melting is not a purity test
Melting a piece does not tell you what it is. A gold-plated brass ring melts at brass’s range and the plate disappears into it; a 9K ring and an 18K ring both melt well below pure gold. What melting does is destroy everything that is not metal value — the maker’s work, the hallmark that records who tested it, and any stones. Refiners melt metal after it has been bought for its metal content; a melting point says nothing about whether that is the right fate for a particular piece.