1808 Carolus Llll 8R, Authentic?

Cross-eyed It sounds like an older desk top lab XRF. It is kind of small to be the really high power unit now being sold which can produce accuracy of 20 PPM.

How long did the test run? A one minute sampling on a well calibrated new unit is decent to 200 PPM but 10 minutes is optimal for a lab reading of 20 PPM. The hour readings can read to 2 PPM (with risk of damage and a $500 charge). At almost $10 a minute the charges ramp up quickly.

When I go to the laboratory my experience has been no more than 8 full tests with computer correction results per hour. In these cases the resulting report can take about 1 week to receive after the raw lab work is complete.

The raw results are always altered by the final computer resolution of the results to eliminate false level detections.

In 2 minutes what you received was a raw test. Did the report include a statement of range of accuracy +/- for each element?

That would be good to know. If say the results are accurate to the 3rd decimal place it would not mean the coin was genuine and it would make the very high silver readings very hard to account for.

Cross-eyed The identification of the unit as a Quickshot RXF,79T+ is adequate to establish the accuracy of the device for the purpose at hand.

It is a desktop version of a Handheld unit that was specifically designed as a GOLD tester. The large chamber was made to accommodate larger objects for testing. The unit has a focusing feature to allow spot testing of various points on the object. It costs about $3,500 brand new and far less on the secondary market.

The level of repeatable accuracy has a stated standard deviation of 0.3 to 0.9%. The results are therefore within almost 1 percent plus or minus.

The unit is not a laboratory type testing device and will not produce a correct alloy profile for silver coins. The results are subject to the same corrections that must be applied to a Handheld unit. So my initial appraisal of the data was correct.

This unit was designed for gold buyers and for that purpose it is very a good instrument. The standard deviations are acceptable for buying gold salvage. It is also adequate to establish that a silver item has the requisite gold content to show that it MIGHT be genuine. Likewise it is adequate to identify as a counterfeit a coin that does not contain the requisite amount of gold.

Therefore an authentication unit for older pre-modern coins it is OK as long as you are interested in gold levels. If you were trying to identify an 1830 silver 8R made in Birmingham, England your project would be a complete failure.

Does the coin dealer buy silver scrap using this same apparatus to establish his purchase price? If he does he needs to increase his margin or he will make less profit than he anticipates.

Also a sharp seller could defraud him if he boiled 500 fine silver in an acid that would leach out the surface copper to a depth of more than 50 microns. Tests I have seen can take a 500 fine coin and make it appear to be 900 fine after a period of about 6 hours. Of course the porosity of the surface has to be rolled or hammered flat. This would not work on most coins but would in theory work very well on scrap silver.