Did Archimedes Invent the Karat System of Grading Gold?

Recycle and Refine GoldRecycle Precious Metals
Written By Barry Lenson

Many people believe that Archimedes (c. 287 – c. 212 BC), the Greek mathematician and scientist, invented the karat system of classifying the purity of gold that is still used today. Although he was a historically important astronomer, engineer, inventor, and mathematician, he didn’t!


However, he did make a significant discovery that is still important to know about if you are someone who invests in gold.

What Archimedes Really Did Discover (Or So We Are Told)

According to legend, Archimedes was asked to determine whether a metal wreath was made of pure gold. It was a hard determination to make because the wreath was constructed of metal leaves attached to a ring made of metal. What metals did it contain? How could he decide how to analyze the ornate wreath without melting it down?


Archimedes knew that pure gold has a specific gravity that is higher than most other metals, so he came up with a method to determine whether the wreath's density was the equivalent of gold’s.


According to the story, he got into a bathtub and noticed that the water level rose as he got in. This led him to realize that the volume of water displaced by his body was equal to the volume of his body. He then applied this principle to the wreath by lowering it into a tank of water and measuring the volume of water it displaced. 


We don’t know exactly how, but by performing this experiment he determined that the wreath was not made of pure gold but was instead made of a less valuable alloy. He was one smart fellow.  


While Archimedes' discovery did not specifically relate to gold, it did demonstrate the principles of volume displacement and density, which are important in understanding the properties of items made of gold and other metals. 


Today, the principle is known as Archimedes' Principle and helps calculate the density of objects, including those that are made of gold.


One Way to Use the Archimedes Principle to Analyzing Metal Objects


Unfortunately, many of the objects found by precious metal investors are complex in shape. What exactly is the volume of material found in, say, a piece of jewelry, a pair of eyeglass frames, or even the gold case of a watch?


Archimedes made it easy to make this determination. You simply place the object into a bath of water and measure the volume of the water that the object displaces. This is an easy test to perform if you have a glass cylinder known as a graduated cylinder, which has markings incised on its side. 


If you drop in, say, an 18K gold wedding ring, you can easily measure its volume and then determine the total amount of gold the ring contains.


This might sound complicated, even though Archimedes made the principles of specific gravity and displacement easy to comprehend. 


If you have any item made of precious metal – even an item that has a complex shape – we can make it even easier to know just how much gold that item contains.  Call our precious metal refiners at 800-426-2344 and we will explain how we will test your item and send you a report that details exactly its content. 


We won’t have to take your item into a bathtub with us! But be assured, our modern testing protocols will tell you the value of your items at current trading prices.  

Barry Lenson
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