Gold-plated jewelry have become increasingly popular due to their affordable prices and exquisite look. However, some shoppers wonder whether grams of gold of these products are exaggerated or not. With multi-applications X-ray fluorescence spectrometers of CFAN Instrument, we explore the true grams of gold of a sample through non-destruction testing.

Distinctions between the gold-filled and the gold-plated

The essential distinctions lie in the thickness of the gold layer and the manufacturing method. 

• Gold-filled

The gold-filled refers to the gold layer (hundreds microns in thickness) mechanically bonded onto the base metal with pressure or heat. This method is commonly used in high-end jewelry. They tend to be pricier, while offer superior durability and corrosion resistance.

• Gold-plated

The gold-plated deposits gold ions onto the base metal to form an ultra-thin gold layer (a few nanometers to a few micrometers in thickness). Because of the lower cost, it is suitable to manufacture accessories and electronic components.

• Hollow gold

The hollow gold refers to depositing a thick layer of gold (50-200 microns in thickness) onto a wax or alloy mold to create the outer shape and then empty the piece. It allows such jewelry with a larger size.

• Novel gold-plated

The novel gold-plated makes full use of the electroplating technique to form a relatively thick layer of gold (5 to 30 microns in thickness) onto the base metal. Grams of gold is determined by the difference in weight before and after electroplating.

Two issues would be discussed in the following:

1. How to compute the grams of gold of a gold-plated sample through non-destructive testing?

2. How to distinguish the gold-plated from the gold-solid?

Issue one, how to compute the grams of gold of a gold-plated sample?

Solution: new series of XF-A5S/XF-A5SMC/XF-S5/XF-S5MC/XF-S6 in 2024

For example, XF-A5SMC Spectrometer is able to accurately and non-destructively detect coating thickness of gold-plated items, which provides an important date for calculating the true weight of gold. It helps consumers identify the true value of such pieces. 

This certificate claimed that this sample contained 1.35 grams of gold.

Through multipoint testing, XF-A5SMC Spectrometer explored an uneven plating and revealed that the average thickness of the gold-plated layer was 24.165 um.

According to the geometric properties of the bracelet, the actual gold weight was computed about 1.182 grams which is 0.168g less than the nominal weight on the certificate.

Conclusion for issue one：

Only gold-plated jewelry with regular shapes can be calculated for gold weight with help of XF-A5SMC Spectrometer. 

As shown above, three X-ray photons respectively excite the first characteristic X-ray of a gold atom, the characteristic X-ray of a silver atom, and the second characteristic X-ray of a gold one following the characteristic X-ray of a silver one. The characteristic X-rays of two gold atoms form the corresponding element spectrum.

If the gold layer is too thick, X-ray cannot reach the silver base or characteristic X-rays of silver cannot penetrate the gold layer to be detected. In this case, the spectrum of silver cannot be collected.

Spectrometers can detect characteristic X-rays of silver atoms with the thickness of layers less than 30 microns. However, characteristic X-rays of silver are unable to penetrate thicker gold layer, for example, 40 microns in thickness, to detect the base metal. In this case, strengthening the energy of X-rays will help characteristic X-rays to be detected.

Issue two, how to distinguish the gold-plated from the gold-solid with non-destructive testing?

Two situation:

• When the thickness of the gold layer is between 15-30 microns, XRF can detect silver atoms and may give a result on a basis of a K gold piece. 

• When the thickness is greater than or equal to 50 microns, XRF cannot detect silver atoms and may give a result on a basis of a solid gold piece.

For the former situation, leveraging the Smart Fundamental Parameter (FP) method, devices will compare the spectrum collected by the detector with the calculated spectrum to distinguish the gold-plated from the K gold.

For the latter, strengthened characteristic X-rays of silver may be able to penetrate thicker layers to be detected.

Gold-pated jewelry offers cost-effectiveness and gorgeous look at the same time. However, certain merchants may exaggerate gold weight of these products or sell them as gold solid ones. Please make rational consumption decisions to avoid risks.