How We Test Gold — Accurate, Non-Destructive XRF Testing in Auckland

Article published at: Sep 2, 2026 Article author: Afshan SEO
All News
How We Test Gold

When you bring your gold to TJ Diamond, the first thing we do is test it. Every piece, every time — no exceptions. We use XRF (X-ray fluorescence) technology, and we do it in front of you, so you can see exactly what we find.

There are no surprises, no back-room assessments, and no acid testing that scratches or damages your jewellery. You watch. You see the result. You get an offer based on what the test actually shows.

What Is XRF Testing?

XRF stands for X-ray fluorescence. It is the same technology used by government assay offices, customs agencies, and professional gemological labs worldwide to determine the precise metal content of any alloy.

The XRF machine directs a small beam of X-rays at the surface of your gold. The atoms in the gold absorb and then re-emit energy at specific wavelengths — each element emits at a unique wavelength. The machine reads those wavelengths and calculates the exact percentage of each metal present in the alloy.

The result: a precise readout of your gold's purity — 37.5% for 9ct, 75% for 18ct, 99.9% for 24ct — in under 60 seconds.

Why XRF Is Better Than Acid Testing

Acid testing was the traditional method for checking gold purity. It involves scratching the item against a test stone and applying acid to the resulting mark to observe the reaction. Acid testing is:

  • Destructive — it scratches the surface of your jewellery.

  • Less precise — it identifies a general karat range, not an exact purity percentage.

  • Slower — each test takes several minutes.

  • Subjective — the result depends on the operator's interpretation of the acid reaction colour.

XRF is none of these things. It is non-destructive, precise to two decimal places, fast, and completely objective — the machine gives the same result every time for the same piece.

The TJ Diamond Testing Process — Step by Step

  1. You bring your gold to our Auckland studio. No appointment needed.

  2. We place each piece into the XRF machine, one at a time, in front of you.

  3. The test runs for 15 to 60 seconds depending on the piece.

  4. The machine displays the exact purity of the gold — the percentage of gold and all other metals present.

  5. We weigh the piece on our certified precision scales — to the nearest 0.01 gram.

  6. We calculate your offer: weight × gold percentage × today's spot price, minus deductions for any non-gold components.

  7. We show you the full calculation and present you with a clear offer. No hidden numbers.

What XRF Can and Cannot Tell Us

  • XRF tells us: the exact gold purity, the presence of other metals (silver, copper, palladium, rhodium, nickel), whether the piece is solid gold or plated.

  • XRF cannot tell us: the internal structure of hollow pieces. For hollow items, we assess volume and wall thickness to estimate actual gold weight.

  • Gold-plated items: XRF identifies plating immediately. A gold-plated piece typically reads a thin gold surface layer over a base metal. These items cannot be purchased as gold — the gold content is negligible.

All XRF testing at TJ Diamond is free and carries no obligation to sell. If you bring your gold and don't like the offer, you take your gold home. The testing changes nothing — it simply tells us both what we are working with.

 

Share: