How to Test Gold Purity Safely: The Hidden Danger of Traditional Gold Testing Methods

Gold purity cannot be confirmed reliably from appearance alone. Hallmarks, invoices and simple home observations can provide useful clues, but professional testing may be needed when authenticity, purity or value must be established.

This guide explains common gold checks, their limitations and how to reduce the risk of damaging jewellery during testing.

What Do 916 and 999 Mean?

• 916 gold (22K) contains approximately 91.6% gold.
• 999 gold (24K) contains approximately 99.9% gold.

The remaining percentage in 916 gold normally consists of other metals that affect strength and colour. A purity mark is useful, but a stamp by itself does not prove that the entire item has the stated composition.

Checks You Can Make Without Damaging the Item

1. Inspect the markings

Look for marks such as 916, 22K, 999 or 24K, usually near a clasp or inside a ring. Also check for a maker’s mark or other identifying information. Very small marks may require magnification.

A missing mark does not automatically mean an item is fake, and a stamped mark can be copied. Treat markings as one piece of evidence rather than a final result.

2. Review the purchase documents

Check the invoice, product description, stated weight, purity and any certificate supplied with the purchase. Confirm that identifying details match the item. Keep these records because they may be useful for warranty, insurance, resale or trade-in enquiries.

3. Look for visible wear or colour differences

Examine high-contact areas, edges and clasps for peeling, flaking or a different colour beneath the surface. These signs may indicate plating, repair work or mixed components, but visual inspection cannot determine exact purity.

4. Use a magnet only as a limited screening check

Gold itself is not strongly magnetic, but a magnet result is not conclusive. Clasps, springs and internal components may contain other metals, while many non-gold metals are also non-magnetic. Do not use a strong magnet near watches, electronics or items that could be damaged.

Traditional Testing Methods

Touchstone and acid testing

In a touchstone test, a sample is rubbed onto a testing stone and exposed to acid solutions. When performed correctly by a trained person, it can help estimate purity. However, it may leave a small abrasion or require access to the underlying metal, and acids require careful handling.

File or cut testing

Filing or cutting may help reveal plating or a different underlying metal, but it is destructive and can leave a permanent mark. It should not be performed without the owner’s informed agreement.

Electronic testers

Electronic conductivity testers can provide an indication of purity, but results depend on calibration, contact, surface condition, item shape and the tester’s limitations. They should not be treated as infallible.

What XRF Testing Can—and Cannot—Tell You

X-ray fluorescence (XRF) can analyse the elemental composition of the area being scanned without cutting or scraping the item. It is widely used as a fast, non-destructive screening method for precious metals.

However, XRF primarily measures the surface and near-surface region. Results can be affected by plating, coatings, solder, mixed components, curved surfaces, item thickness, calibration and the exact area tested. A single scan may not represent the entire item.

For that reason, a responsible assessment may include scans at several points, visual inspection, weight and dimension checks, documentation review or another suitable test. The tester should explain the method used and any limitations.

How to Choose a Gold-Testing Service

Before testing, ask:

• Which method will be used?
• Could it mark or alter the jewellery?
• Will multiple areas or components be checked?
• Will the findings be explained or documented?
• Are testing fees or valuation conditions involved?

Testing results and a buy-back quotation are separate matters. A purchase or trade-in offer can also depend on verified weight, condition, prevailing rates, refining costs and the buyer’s terms. No testing method guarantees the highest payout.

Gold Assessment at Best Gold Shop

Best Gold Shop can inspect gold items at 38 Joo Chiat Road, Singapore 427366 and explain the available assessment or trade-in process. The appropriate method depends on the item and the purpose of the assessment. Any quotation should be confirmed after inspection and according to the applicable terms.

You can also review our certificate verification page, published gold prices, and 916 gold or 999 gold collections.

This guide provides general information. Do not handle testing acids or damage an item to test it at home. Seek qualified advice for valuable, antique, stone-set or unfamiliar jewellery.