THE SHORT ANSWER
XRF is a surface-composition measurement, not an authenticity verdict
X-ray fluorescence identifies elements from the instrument's measurement region and estimates their proportions through a calibrated model. It is fast and usually non-destructive, which makes it useful for screening jewelry, coins and bars. Its decisive limit is depth: LBMA says gold's X-ray penetration is generally less than 10 microns in this context, so plating, surface enrichment, solder, contamination and an unrepresentative spot can misstate the whole object.
METHOD BOUNDARY
Separate the observation from the conclusion
READ THE REPORT
Keep eight fields with every XRF number
OBJECT-SPECIFIC TRAPS
One clean reading can be the least representative reading
A clasp, solder joint, plated face, polished high point and concealed interior are different analytical regions. Jewelry can combine several alloys and non-metal components. A minted bar can present a convincing gold surface over another structure. A cast bar may be compositionally homogeneous near the surface while containing pores or inclusions that XRF cannot map.
Multiple sites improve coverage but do not create depth. If the decision depends on the interior, pair surface composition with geometry or a qualified interior method. If the decision requires fineness of the bulk material, a representative sampling and laboratory plan may be necessary.
PRIMARY AND STANDARDS SOURCES
Methods are only as strong as their scope and controls
- LBMA Physical Market Guidelines distinguish surface XRF, ultrasound, eddy current and representative destructive analysis. LBMA states that no definitive non-destructive solution is currently endorsed.
- NIST reference materials and NIST gold-alloy SRMs illustrate why reference material, calibration and a defined analytical scope matter.
Sources reviewed July 31, 2026. Instrument procedures, safety data, standards and acceptance criteria can change. Use the current method documentation for the exact item, instrument, laboratory and decision.
FREQUENTLY ASKED QUESTIONS
XRF gold testing questions
Does XRF prove a gold item is solid gold?
No. XRF measures a shallow region near the surface. LBMA notes that gold strongly absorbs X-rays and warns that surface analysis can be deceived by plating.
Is XRF gold testing non-destructive?
It is generally described as non-destructive, but preparation, cleaning, filing or exposing a representative area can still alter an item. Record exactly what was done.
Why can two XRF readings differ?
Calibration, instrument geometry, measurement time, surface condition, coating, matrix, spot location and operator procedure can all change the reported result.
Can XRF report gold karat?
An instrument can translate measured elemental composition into fineness or karat under a defined method, but that number applies to the measured region and model assumptions—not automatically the whole item.