U,Th-He dating of gold
Universität Bern's mass spectrometer.
Why And When To Use The Test
This test can be used on objects which are primarily gold, even if alloyed with silver and/or copper. If the method of manufacture involved heating the gold above a critical temperature, then the metal may be suited to testing. It can be used after an object has passed other non-destructive tests and examinations, such as composition, method of manufacture, and weathering/wear patterns. Samples might also be submitted if there was any questionable result from a previous test, or if one would, perhaps, simply wish to contribute (at roughly $4000 cost) to the general database.
Advantages & Disadvantages
The application of this test to art and artifacts is in its infancy. As such, at present, there are more cons that pros, but that balance should change as more samples are tested, and advances are made.
- On suitable samples, it can provide excellent evidence of age, just by itself.
- Used in conjunction with other examinations, it can provide evidence of authenticity of a gold object.
- It can provide a date on objects as young as approximately 150 years in age, and as old as several thousand years.
- As the margin of error for the technique is improved, it should help identify copies made in antiquity, which are of historic interest, from modern forgeries.
- Though the required sample size is only 30mg, it is considered a destructive test.
- It is expensive (currently 3000 Euros).
- It requires a minimum of approximately two months to obtain results, and often takes longer.
- The margin of error is currently around +/- 30%.
- It is not suited for use on some types of gold, but the parameters for consistently identifying that type of gold, before testing, have not yet been established.