How Gold-Testing Machines Work: A Practical Guide for Sellers

Author : nani pvs | Published On : 30 Jul 2026

When you take old jewellery to a gold buyer, one of the first questions is usually about purity. Is the ornament really 22 karat? Has a repair changed its metal content? Does the chain contain only gold, or is it mixed with silver, copper, zinc, or other metals?

These questions cannot be answered accurately by appearance alone. Gold colour may vary according to the metals mixed with it, and two ornaments that look almost identical may have different purity levels.

Modern gold-testing machines help buyers examine the elemental composition of jewellery and estimate its purity before calculating a value. Understanding how these machines work can help sellers follow the process and ask the right questions.

Why Gold Purity Must Be Tested

The value of old jewellery depends heavily on the amount of actual gold it contains.

Pure gold is soft, so jewellery manufacturers generally mix it with other metals to improve strength, durability, colour, and wearability. Common alloying metals include silver, copper, zinc, nickel, and palladium.

This is why jewellery is sold in different purity levels:

24 karat: Nearly pure gold, generally used for coins and bars
22 karat: Commonly used for traditional Indian jewellery
18 karat: Frequently used in modern and stone-studded ornaments
14 karat: Contains a lower proportion of gold and more alloy

A 20-gram ornament made from 22-karat gold will not have the same gold content as a 20-gram ornament made from 18-karat gold. Testing is therefore necessary before the buyer can apply the appropriate purity-based rate.

What Is an XRF Gold-Testing Machine?

Many organised gold buyers use an X-ray fluorescence machine, commonly called an XRF analyser or spectrometer.

An XRF machine examines the elemental composition of a metal. It can identify gold and other metals present in an ornament and estimate their proportions. Gold-testing applications use this information to determine purity, karat classification, and alloy composition.

Unlike a traditional acid test, XRF testing generally does not require the jewellery to be scratched, cut, or melted during the initial assessment. This makes it useful for examining rings, chains, bangles, coins, earrings, watches, and other precious-metal items.

How XRF Testing Works

The science behind XRF may sound complicated, but the basic process can be understood in a few steps.

Step 1: The Jewellery Is Positioned in the Machine

The ornament is placed inside the testing chamber or against the testing window, depending on the type of analyser being used.

The staff member chooses a suitable area of the ornament for testing. Ideally, the selected surface should be clean, reasonably flat, and free from stones or decorative material.

For ornaments with several sections, the operator may need to take readings from more than one point.

Step 2: The Machine Directs X-Rays at the Metal

The analyser sends controlled primary X-rays toward the jewellery.

When these X-rays interact with the atoms in the metal, they displace electrons from their normal positions. Other electrons then move to fill those vacancies and release energy in the form of secondary, or fluorescent, X-rays.

Step 3: Each Element Produces a Recognisable Signal

Gold, silver, copper, zinc, palladium, and other elements release fluorescent X-rays with distinctive energy patterns.

These patterns work like elemental fingerprints. The detector inside the machine measures the energy and intensity of the signals and identifies which metals are present.

Step 4: The Software Calculates the Composition

The analyser’s software processes the detected signals and displays an estimated breakdown of the alloy.

A result may show percentages for:

Gold
Silver
Copper
Zinc
Nickel
Palladium
Rhodium
Other detectable metals

From the gold percentage, the system can estimate the jewellery’s fineness or karat level.

The result helps the buyer decide which purity category and gold rate should be used during valuation.

What Information Does the Machine Show?

The exact screen and report depend on the equipment, calibration, and software. A precious-metal analyser may display:

Percentage of gold in the tested area
Percentage of other metals
Estimated karat value
Alloy identification
Warnings about plating or unexpected metals
Test duration and reading details

Modern precious-metal XRF analysers are designed to deliver elemental composition and karat information quickly without damaging the tested item.

As a seller, you should not be shown only the final amount. Ask the staff member to explain what the purity result means and how it affects the valuation.

Why Jewellery May Contain Several Metals

Gold jewellery is rarely made from gold alone.

Other metals are added for practical and visual reasons. Copper can add strength and a warmer colour. Silver can make the alloy lighter in appearance. Palladium or nickel may be used in white-gold compositions.

An XRF result showing copper or silver does not automatically mean the jewellery is fake. These metals may be normal parts of the alloy.

What matters is the percentage of gold present and whether the measured composition is consistent with the claimed purity.

For example:

22-karat gold contains a higher gold proportion than 18-karat gold
18-karat jewellery contains more alloying metal than 22-karat jewellery
White gold may contain palladium, nickel, silver, or other pale-coloured metals
Repaired areas may contain solder with a different composition

The buyer should explain the result instead of treating every non-gold metal as an unexplained deduction.

Why Multiple Readings May Be Necessary

A single reading may not always represent an entire ornament.

Jewellery can contain different sections, including:

Soldered joints
Repaired links
Clasps and hooks
Stone settings
Decorative plates
Added extensions
Replaced components
Surface coatings

A chain clasp, for instance, may have a different composition from the main chain. A resized ring may contain solder at the joint. A bangle may have been repaired more than once.

Testing several suitable points can provide a better understanding of the ornament’s overall composition. This is particularly important for old, altered, plated, or heavily repaired jewellery.

Can an XRF Machine Test Below the Surface?

XRF is primarily a surface-analysis technique. The result is strongly influenced by the area exposed to the analyser.

Surface coatings, contamination, plating, and differences between sections can affect the reading. Thermo Fisher’s technical guidance notes that inhomogeneity or surface contamination can skew XRF results because the tested surface may not represent the complete object.

This does not make the technology unreliable. It means the equipment must be operated correctly and the result must be interpreted by trained staff.

When an ornament appears plated, unusually constructed, or inconsistent, the operator may:

Test several points
Examine an uncoated area
Inspect the item carefully
Use equipment with plating-detection capability
Apply an additional verification method

Specialised XRF systems can alert operators to certain plating conditions, although thick coatings or complex items may require secondary analysis.

Does XRF Testing Damage Jewellery?

XRF testing is generally described as a nondestructive method. The machine analyses the metal without requiring the initial sample to be scratched or dissolved in acid.

This is one reason the technology is commonly used in jewellery stores, gold-buying businesses, refineries, pawn businesses, and precious-metal trading environments.

However, the seller should still observe how the ornament is handled. Testing equipment should be operated by trained personnel, and the jewellery should remain secure and identifiable throughout the assessment.

XRF Testing Versus Traditional Acid Testing

Traditional gold testing often involves rubbing the jewellery on a touchstone and applying acid solutions to the resulting mark.

This method may provide a broad purity indication, but it depends considerably on operator judgement. It may also leave a small mark or require contact with corrosive chemicals.

XRF testing offers several practical advantages:

Factor	Traditional Acid Testing	XRF Machine Testing
Testing approach	Scratch and chemical reaction	X-ray fluorescence analysis
Jewellery contact	May require rubbing or scratching	Generally nondestructive
Result type	Broad purity indication	Elemental composition and estimated karat
Operator judgement	Significant	Software-supported analysis
Multiple elements	Limited information	Can identify several metals
Speed	Relatively quick	Results can be produced within seconds

XRF manufacturers describe the technology as a faster and more comprehensive method for precious-metal composition testing than acid-based screening.

The quality of either method still depends on correct procedures, equipment maintenance, calibration, and staff competence.

Does the Machine Determine the Final Gold Value?

The testing machine determines purity or elemental composition. It does not independently decide the complete value of the jewellery.

After testing, the buyer must also consider:

Net Gold Weight

Stones, beads, threads, springs, enamel, lac, and other non-gold components may be excluded from the payable weight.

Applicable Gold Rate

The rate should match the detected purity. A 24-karat market rate should not be applied directly to lower-purity jewellery without adjustment.

Jewellery Condition and Construction

Repairs, solder, plating, and mixed components may require additional checks.

Disclosed Deductions

Any adjustment affecting the final amount should be explained before the seller approves the transaction.

The complete valuation therefore combines the machine result with accurate weighing and the applicable live gold rate.

What Sellers Should Watch During Testing

When approaching professional Gold buyers in Bangalore, look for a process that allows you to observe the important stages.

Check whether:

Your jewellery remains visible
The machine is operated in front of you
The tested area is shown
The purity result is displayed
Multiple sections are checked when necessary
The weighing scale starts at zero
Non-gold deductions are explained
The live gold rate is visible
The final offer is reviewed before approval

Technology should make the process clearer. It should not be used to present a number that the customer is expected to accept without explanation.

Questions to Ask the Gold Buyer

You do not need technical knowledge to ask useful questions.

Before accepting the valuation, ask:

Which testing machine are you using?
Is this an XRF spectrometer?
Which part of the ornament was tested?
Were multiple readings taken?
What percentage of gold was detected?
Which other metals were identified?
Does the result indicate repairs or plating?
What karat value does the reading represent?
How does the purity affect the payable rate?
Can I see the result before deciding?

A trustworthy buyer should answer these questions calmly and clearly.

How White Gold Tests Jewellery

White Gold states that its branches use German spectrometers and precision weighing scales to determine the purity and weight of customers’ gold. Its published guidance also says that industry-standard spectrometer machines are used so ornaments can be assessed without relying only on traditional manual testing.

The machine result is only one part of the branch process. Customers should also be shown the applicable gold rate, receive an explanation of the valuation, complete identity verification, and review the final offer before approving the transaction.

Better Technology Should Create Better Clarity

A modern gold-testing machine can identify the metals present in jewellery and provide a quick estimate of its purity. XRF technology does this by measuring the distinctive fluorescent X-rays released by the elements in the tested surface.

For sellers, the main benefit is not simply speed. It is the ability to see a machine-based purity result and understand how that result connects to the final valuation.

Before selling old gold, choose a buyer who performs the test visibly, explains the reading, checks different sections where necessary, weighs the jewellery accurately, and clearly shows how the final value was calculated. The equipment matters, but transparent handling and a proper explanation matter just as much.