Does Gold Purity Change When Jewellery Is Repaired or Resized?

Does Gold Purity Change When Jewellery Is Repaired or Resized?

Your necklace has been repaired, a ring has been resized, or a clasp has been replaced. Now you want to sell the piece. A common question: does the repair affect the gold's purity - and therefore what you receive?

The answer depends entirely on how the repair was done and what materials were used. Here is a clear breakdown.

At a Glance

How Different Types of Repair Affect Purity

The KDM Era: Why Old Repaired Jewellery Tests Lower

Before the BIS banned cadmium-based solder in India (around 2000–2001), most jewellers used KDM solder - a cadmium-tin alloy - to join gold pieces. Cadmium is significantly cheaper than gold and lowers the overall gold content of the piece wherever it was used.

This is why many pieces of jewellery repaired before 2000 test at 20K–21K rather than the expected 22K. The cadmium solder mixed with the gold at the repair points pulls down the average purity reading.

XRF testing is honest about this - it reports the actual composition. A piece that XRF-reads at 87% gold (≈21K) is paid at the 21K rate, regardless of what the original hallmark said.

What Happens During XRF Testing of Repaired Jewellery

• XRF tests a specific spot on the piece - the result reflects the composition at that point
• If the tester tests at the solder join, a lower gold% may show
• If the tester tests on the main body of the piece away from any join, the result reflects the base metal purity
• Reputable buyers test multiple spots and use the average, or test the main body
• Ask where the XRF probe was placed - this matters for repaired pieces

What to Do If Your Gold Was Repaired

• Tell the branch staff that the piece has been repaired - they can test multiple spots
• Ask what karat the repair material was - a jeweller who used same-karat gold solder can confirm this
• If the repair was done professionally with same-karat gold solder, purity should be unchanged
• If you suspect old KDM solder was used, expect the XRF to show slightly lower purity

Why Choose Attica Gold Company

Attica Gold Company is ISO 9001:2015 certified with 200+ branches across Karnataka, Tamil Nadu, Andhra Pradesh, Telangana and Pondicherry. Your wait is over.

Frequently Asked Questions

Does repairing gold reduce its value?

Only if the repair used lower-purity or non-gold solder. Modern gold-to-gold repair with same-karat solder should not reduce purity.

What is KDM solder and why does it affect purity?

KDM solder contained cadmium - a cheaper metal - which was used to join gold pieces before 2001. It reduces the overall gold content in the repaired area.

Can XRF detect soldering?

Yes - XRF identifies the composition wherever the probe is placed, including solder joints. A cadmium or silver solder join will show clearly in the result.

If my jewellery was resized, does the purity change?

Resizing by stretching or compressing changes the shape but not the purity. Resizing by cutting and re-joining (with solder) may affect purity depending on the solder used.

Does rhodium plating affect gold purity?

No - rhodium plating is a surface treatment that does not change the gold alloy beneath. XRF penetrates the plating and reads the gold content correctly.

What should I tell the branch when selling repaired jewellery?

Mention that the piece has been repaired. The staff will test at multiple points to ensure an accurate purity assessment.

Why does my old gold test at 20K when I thought it was 22K?

Old KDM solder (pre-2001) commonly contains cadmium that dilutes the gold content. This is one of the most common reasons old pieces test below their expected purity.