We’ve all heard that old tale of how the term “Eureka!” was coined by Archimedes. You know the one where he was getting into the bathtub, noticed the displaced water level and jumped up exclaiming the now famous phrase, “Eureka – I have found it!” What many forget to mention in this story is the problem Archimedes was pondering in the suds to begin with – gold! Specifically, Archimedes was given the task to prove that a certain golden crown commissioned by Hiero of Syracuse was, in fact, made of pure gold, and not (as he suspected) an impure mixture of gold and silver.
As all gold buyers are well aware, not all that glitters is gold, and there are many cheap imitations on the market. Thankfully, if you are looking to sell your gold jewellery, there are a few easy tricks to test how pure it really is.
1: Density test
As Archimedes discovered, gold is incredibly dense, therefore won’t float. If your jewellery floats in a glass of water, it isn’t gold. That being said, several other metals will sink as well, so this is not a definitive test. The trick is to calculate the actual density, as Archimedes noted when he immersed himself into the tub. Fill a clear glass with water and take note of the water level, drop in your gold item and the take note of the new water level. To find out the density of your gold, divide the weight of your gold by the difference in water level (in millimetres). If the resulting value is close to 19.3 g/cm3 (the density of gold), you’re good to go.
2: Take a bite
We’ve all seen those old films where mobsters or gold prospectors attempt to take a bite out of a piece of gold to verify its purity. This isn’t the stuff of fiction. Gold is in fact rather soft and if your teeth leave marks, you’re sitting with pure gold. Just remember not to bite too hard in case you hurt your teeth.
3. Take a good look
Take a good look at your gold, often there will be tell-tale markings indicating the purity of your piece. This is usually in the form of a stamp indicating karat weight. Another sign is discolouration, particularly from friction; gold-plated pieces may, in time, rub off and show signs of wear.
Main image: Pixabay.com