How to tell if it's real gold

SINGAPORE - Those dealing with gold on a regular basis are often able to tell the real McCoy by touching and holding it.

But this is often very subjective and fake or low-grade gold can often slip under the wire.

Those unsure about the grade of their precious metals, like gold, silver, platinum or palladium, can send them for testing at the Singapore Assay Office (SAO) for a fee.

The fee varies based on quantity.

Testing is needed here because unlike in some countries such as Britain, the quality of precious metals sold here does not have to be verified or hallmarked.

When an item has been verified to be of satisfactory quality, it is marked with the laboratory's logo.

Here are 3 ways the quality or fineness of gold can be tested:

1. Touchstone/carat needles

An ancient way of testing that dates back to 500BC. Gold is rubbed against a dark stone, usually quartz or jasper, which leaves a mark on the stone.

That mark is compared with a similar one made by a real piece of gold.

Next, a few drops of nitric acid are added onto the mark. As gold is a non-reactive metal, the mark will remain on the stone.

This is usually followed by aqua regia (a mix of nitric acid and hydrochloric acid), which will make the mark disappear.

Most pawnshops and traditional jewellery shops still use this testing method.

2. X-Ray Fluorescence (XRF)

This is a non-destructive method. It puts the gold pieces through a simple X-ray machine. From the result, jewellers are able to tell the amount of gold in a piece, as well as what impurities it contains.

3. Fire assay

A small sample is taken from the gold and smelted down. Base-metals, such as iron and lead are removed, leaving a gold-silver mixture.

The silver is then removed, leaving pure gold, which is then measured. While it means that the testing sample cannot be used again, this is the most accurate method of assaying gold.