Gold has been cherished and sought after for centuries due to its lustrous beauty and inherent value. Whether you are buying gold from the famous Makorokoza (ASM) across Zimbabwe or selling gold, or simply wanting to verify the authenticity of your gold investment, it is essential to know how to test for gold authenticity. Many have lost funds trying to get into the fastest-rising industry in the country getting “Brasso” instead of gold. Some unscrupulous individuals who dupe unsuspecting buyers will add bicycle size “Steel balls” and coat them with real gold to increase the weight of their product. While professional jewellers and gold dealers have access to accurate and sophisticated tests, there are several methods that individuals can employ to evaluate the authenticity of gold.
The first step in testing gold authenticity is to visually examine the item. Authentic gold will have a consistent colour and shine. It should not appear overly dull, tarnished, or discoloured. While some variations in colour may exist due to different karat levels, be cautious of gold that appears too light or too dark, as it could be an indicator of counterfeit or impure gold.
Gold is not magnetic, so using a magnet is a simple yet effective test for gold authenticity. Hold a strong magnet close to the gold item and observe whether there is any attraction. If the item is attracted to the magnet, it is likely not made of authentic gold.
Gold is a dense metal, and its purity can be tested by comparing its density with a known authentic gold sample. To perform this test, sign up for a gold density testing kit, which typically includes a beaker, precise measurements of distilled water, and a specific procedure to follow. By accurately measuring the displacement of water when gold is submerged, one can determine its density and purity level.
Acid testing is a widely-used method to verify gold authenticity. However, it is important to exercise caution and perform this test only with appropriate safety measures as it involves working with corrosive acids. An acid testing kit can be purchased, which generally includes different acid solutions to test various karat levels of gold. A sample is scratched or rubbed against a test stone, and acid is then applied to the streak mark. The reaction observed will help determine the gold’s purity.
For more accurate and advanced testing, X-ray fluorescence (XRF) analysis is the go-to method. XRF analyzers can be expensive and require professional expertise; hence, it is typically employed by professionals such as jewellers, pawnshops, and gold refineries. These machines use X-rays to determine the elemental composition and purity of the gold accurately.
The float test
Just drop the piece into a container of water. Gold is dense. If it doesn’t float at all or hover over the bottom of the container, you could possibly have real gold.
A ceramic scratch test
Take an unglazed ceramic plate or piece of tile and scrape a piece of gold across its surface. Real gold will leave a gold mark or trail. Other metals will leave a black trail.
The density test
This is done by calculation. You need
- A scale (to weigh the jewellery)
- A container of water and
- A way to measure the level in millimetres (to measure the water levels before and after the jewellery goes into the water)
Now do the calculation: subtract the “before” measurement from the “after” measurement. Then divide the weight of the jewellery by the difference in the water levels.
This gives you the density.
The standard density of real gold is 19.3 grams per milliliter (also written 19.3g/mL). Not a lot of other metals come very close to it. If your calculation gives this figure or something very close to it, you probably have real gold.
When you use density to distinguish gold’s authenticity, you also need to keep in mind that there can be differences in density between different types of gold.
For example, the purer the gold, the heavier it will be–and white gold is heavier than yellow. Therefore, the density of gold between 14k and 22k will be anywhere between around 12.9 and 17.7 for yellow gold and anywhere between around 14 and 17.8g/mL for white gold.
This test simply requires that a few drops of vinegar be applied to the metal, hopefully in an inconspicuous place.
If the metal is real gold there will be no change. If the metal is fake gold it will change color.
Fire assay is considered the most reliable method for accurately determining the content of gold, silver, and platinum-group metals (except osmium and ruthenium) in ores or concentrates. This process involves melting a gold-bearing sample in a clay crucible with a mixture of fluxes (such as silica and borax), lead oxide (called litharge), and a reducing agent (frequently flour). The fluxes lower the melting point of the oxidic materials, allowing them to fuse, and the molten litharge is reduced by the flour to extremely fine drops of lead dispersed throughout the charge. The drops of lead dissolve the gold, silver, and platinum-group metals, then coalesce and gradually descend through the sample to form a metallic layer at the bottom of the crucible. After cooling, the lead “button” is separated from the slag layer and heated under oxidizing conditions to oxidize and eliminate the lead. The shiny metallic bead that is left contains precious metals. The bead is boiled in nitric acid to dissolve the silver (a process called parting), and the gold residue is weighed. If platinum metals are present, they will alter the appearance of the bead and their concentration can sometimes be determined by the use of an arc spectrograph.
While these testing methods can provide helpful insights into gold authenticity, it is crucial to note that some counterfeiters are becoming more sophisticated in replicating authentic gold. Therefore, it is wise to seek professional assistance from a reputable jeweller or gold dealer if you are uncertain about the authenticity of your gold.
In conclusion, testing gold authenticity requires a combination of visual inspection and various tests, including magnet, density, acid, and XRF analysis. Familiarizing yourself with these techniques will help you make more informed decisions when buying or selling gold, ensuring that you possess genuine pieces that hold their inherent value.