99.9%
Percentage
Gold Purity Testing
Gold Purity Testing
Independent purity and composition testing for suitable bullion, doré, jewellery and other precious-metal materials.
Bilex selects the testing method according to the material and the level of information required.
How Gold Purity Is Expressed
999
Fineness
24K
Karat
These are different ways of describing gold content. Testing provides measured information for the material examined.
Materials We Test
Bullion
Finished gold bars and suitable solid bullion.
Doré
Gold-silver and other precious-metal mixtures.
Jewellery
Suitable finished items requiring composition or purity assessment.
Other Metallic Materials
Other suitable gold-bearing metallic samples reviewed before testing.
Purity Testing Methods
XRF Analysis
Rapid, non-destructive elemental analysis of suitable metallic surfaces.
Fire Assay
Representative gold determination from a prepared sample.
Supporting Verification
Ultrasonic and density testing can provide additional physical evidence for suitable bullion.
What to Expect
Review
Tell us the material and what you want to establish.
Select
Bilex confirms the appropriate testing method.
Test
The agreed analysis or verification is carried out.
Report
You receive a result linked to the material and method used.
Frequently Asked Questions
DOES 24K ALWAYS MEAN 9999 GOLD?
No. 24 karat describes the highest karat category, while fineness expresses gold content in parts per thousand. A marking alone does not establish the measured composition of a particular item.
CAN XRF TELL ME THE PURITY OF A GOLD BAR?
XRF can provide useful elemental information from the measured surface. It does not automatically describe the complete interior of a thick or non-uniform item.
WHEN WOULD FIRE ASSAY BE USED?
Fire Assay may be appropriate when a representative quantitative gold determination is required and sampling is permitted.
CAN BILEX TEST DORÉ?
Yes. The method depends on the form of the material, the testing objective and whether representative sampling is permitted.
CAN YOU TEST A BAR WITHOUT CUTTING IT?
Suitable bars can be examined using non-destructive analytical and physical methods. We will confirm what those methods can and cannot establish before testing.
Book Purity Testing
Tell us the material and what you need the result to establish.
Overview
Purity is a measured result, not a label
Marks such as 24 karat, 999 or 9999 describe a claimed or specified level of fineness. They do not establish the composition of a particular bar or item by themselves. Gold purity testing connects the material to a measured result and a stated method.
XRF for rapid composition
XRF is useful when the item should remain intact and the immediate question concerns elemental composition at the measured surface. Bilex can prepare and polish suitable areas before testing with handheld or desktop XRF equipment. Several areas may be measured where comparison across the item is useful.
Because XRF measures a shallow region, plating, surface enrichment, contamination and internal inserts can limit what the result says about the whole item.
Fire Assay for representative fineness
Where the decision requires a representative quantitative gold result and sampling is permitted, Fire Assay can be performed on a metallic sample taken from the material. In high grade gold and doré work, the assay portion is cupelled and the precious metal bead is treated so that gold and silver can be separated and determined under the applicable procedure. The result is tied to the sample that was taken.
Physical verification for suitable bullion
Ultrasonic and hydrostatic density testing can add useful physical information when the item is a suitable solid bar. Ultrasound looks for internal boundaries and discontinuities. Density testing compares mass with volume. Neither method determines exact fineness on its own, but both can complement elemental and assay evidence.
How results may be expressed
Depending on the material and method, results may be reported as percentage, fineness or another appropriate concentration unit. For ore and concentrates, grade may be reported in units such as grams per tonne rather than bullion style fineness. The unit should always match the material and analytical question.