Several articles regarding how to spot fake gold start with advices like:
- take your gold piece to an expert
- only trade with reliable goldsmiths
- look for a carat mark
Although such advices are not completely wrong, they depend heavily on trust. However, what if the expert you are trusting makes a mistake (intentionally or not), how can you verify his analysis?
"Trust, but verify", President Ronald Reagan
This article is meant for you to be 100% sure that your gold piece is really true, without the need of trusting on 3rd parties.
There is a long list of gold alloys used on jewelry ranging from 30% to 100% purity. Although they are legitimate jewelry pieces, verifying its gold content can be a challenge.
Fortunately, gold as a financial asset, is mainly traded in high purity which is much easier to verify.
In this article the focus will be testing only such kind of gold, ie, high purity gold bars or coins (bullion).
Non-Destructive Test Only
There are several (semi)destructive tests available that are reasonably accurate. The most common one is the acid test, but there are several others: fire assay, plasma spectrometry, etc. However, as the name implies, doing such tests means you partly damage your bullion and loose value. The kind of tests to be discussed in this article are the ones completely non-destructive.
The tests should be done in order of complexity. Whereas each step confirming the necessity of further investigation.
1. Visual Inspection
- Color: Whereas most metals are gray or silvery white, gold has a unique yellow color among metals.
- Oxidation: Gold is a very stable element which almost doesn't react chemically to other elements. Therefore, you shouldn't see any oxidation.
Anything other than an homogeneous yellow surface is suspicious.
Gold is diamagnetic, which means it is slightly repealed by magnets. Therefore, if your metal piece is attracted by a magnet then it is not gold.
3. Specific Density
Gold is one of the densest element out there. There is only one other base metal with a similar density and non-radioactive: tungsten.
Therefore, doing a simple Archimedes test should detect most types of counterfeit pieces. The only exception would be tungsten filled gold pieces, which has several complaints over the internet. This is a real problem and requires additional testing.