Touchstone vs XRF Machine: Which Approach Is Better for Determining Gold Purity?

XRF vs Touchstone are two commonly used methods for assessing gold purity during the loan valuation process. Gold purity testing plays an important role in determining the eligible loan value, as lenders assess the net gold content of pledged jewellery in line with applicable valuation and loan‑to‑value (LTV) norms prescribed by the Reserve Bank of India.

Differences in testing methods, accuracy ranges, and surface sensitivity may influence the purity reading used for valuation. Borrowers benefit from understanding how these methods work and how purity results are factored into gold loan assessments, subject to regulatory guidelines and lender procedures.

Why Gold Purity Testing Matters for Your Loan Amount

In a gold loan, the eligible loan amount is determined based on the assessed value of the gold, which depends on its purity, net weight, and the prevailing benchmark price used by the lender (commonly IBJA‑linked rates).

Under the RBI Lending Against Gold and Silver Collateral Directions, 2025, regulated lenders follow tiered Loan‑to‑Value (LTV) limits that vary based on the loan amount slab. The applicable LTV is applied to the assessed gold value at the time of loan sanction and must be maintained throughout the loan tenure.

Variations in purity assessment—such as whether jewellery is read as 18K, 20K, or 22K, may affect the underlying valuation. Actual loan eligibility depends on lender policy, regulatory caps, and the final purity reading recorded during the assaying process.

How Does an XRF Machine Test Gold?

An XRF (X‑ray Fluorescence) machine is a non‑destructive analytical instrument used to estimate the elemental composition of gold jewellery. The device directs low‑energy X‑rays at the surface of the item, causing constituent metals to emit characteristic signals. These signals are analysed to estimate the proportion of gold and other metals present.

XRF testing typically provides results within seconds and does not involve scratching or chemical exposure. Accuracy levels depend on factors such as instrument calibration, surface cleanliness, and sample homogeneity. Since XRF primarily analyses surface layers, additional checks may be applied by valuers where layered or plated items are suspected.

What the XRF Readout Looks Like

If you go to a branch, you can ask to see the screen during the valuation process. A list of the metals present in your jewellery will be displayed. Au for gold will appear, followed by a percentage. Additionally, it will display a fineness number (such as 916) and a karat value (such as 22K). You should make sure that this digital reading and the BIS hallmark stamp on your jewellery match as a wise borrower.

How Does a Touchstone Test Operate?

The touchstone test, also known as an acid test, is a traditional method used to estimate gold purity. A small streak is rubbed onto a stone, and different concentrations of acid are applied to observe the reaction.

The result is interpreted by comparing the reaction with known reference standards. While this method can help identify obvious plating or base metals, outcomes depend on operator experience, lighting conditions, and acid strength. The process may cause minimal surface abrasion to the jewellery.

XRF vs. Touchstone: A Side-by-Side Comparison

In summary, the XRF machine is the winner for accuracy and keeping your jewellery safe. The touchstone test is still useful for identifying gold-plated items, but lacks the precision of modern technology.

Which Method Does IIFL Finance Use?

At IIFL Finance branches, gold purity assessment is carried out using approved valuation procedures, which may include non‑destructive testing tools such as XRF machines. The valuation process is conducted in the presence of the borrower and in accordance with internal protocols and applicable RBI guidelines on transparency and disclosure.

Where jewellery bears BIS hallmarking, the hallmark details may be used as an additional reference during assessment. Final valuation outcomes are documented as part of the loan processing record, subject to lender policy and regulatory requirement

How to Examine Your Gold Purity Stamp Prior to Going to a Branch

You can verify the purity of your gold before going to a branch. Look for the BIS hallmarking marks, which are typically located on the hook of a necklace or the interior of a ring. You'll observe:

1. The BIS logo is an equilateral triangle.

2. Purity/Fineness: For instance, 18K750 (75% pure) or 22K916 (22 carat, or 91.6% pure).

3. Assaying Centre Mark: The lab's logo is used for the test.

4. HUID: A unique six-digit alphanumeric code.

The HUID is especially important for modern jewellery as it allows the gold's history to be tracked through government records. A professional valuation at a branch should always confirm what these stamps already say.

What to Do If You Disagree with the Purity Reading

If the test results are different from what you expected, do not worry. As a borrower, you have rights. You can do the following:

• Request that the valuer display the XRF readout on the screen.

• Compare the reading to your ornament's BIS hallmark.

• If the jewellery was oily or dirty, request that it be cleaned and retested because surface debris can occasionally alter X-ray readings.

• For very expensive items, you can visit a government-accredited centre for a formal report before you pledge your gold.

• If you still have concerns, speak with the branch manager or contact customer care. A reliable lender will always be happy to explain the valuation process to you.

Disclaimer : The information in this blog is for general purposes only and may change without notice. It does not constitute legal, tax, or financial advice. Readers should seek professional guidance and make decisions at their own discretion. IIFL Finance is not liable for any reliance on this content. Read more