Russia 1913 Rouble XRF Silver Content Too High? Fake Or Real?

Sorry it's taken so long to get images up-I need to retake the reverse in order to upload!

I am honestly troubled. From the photos alone, it looks genuine. The edge is quite hard to duplicate but it doesn't mean that it's impossible. I have a counterfeit Gangut ruble and the edge and weight is close to spot on - the color just looked wrong.

I think it's a bit too early to dismiss it as counterfeit immediately based on the XRF. There isn't any real research of such silver coins. The only one that I can think of straight away is the Russian platinum coins that circulated. The UNC coins proved to be an issue as some were restruck later during the Soviet era to be sold in the Western world. The only way to differentiate the difference is that the restrikes are too pure and the original coins have traces of various metals including iron.

Personally I would suggest finding another example of such commemorative ruble to compare the result. It would be interesting to see if it shows any differences.

It's not so simple as to which coins a counterfeiter makes or why.
Most cases I have are to decieve merchants having base metal core with a silver wash.
Others decieve collectors and will spend $20 for silver to get a $80 or $180 profit.
A different approach made by some counterfeiters, was the South Africa 5 Rand coin, worth I think about 34 cents.
The difference is the nickel is thinner and the core is thicker.
You can pick up the genuine coin with a very weak magnet- not so much with the fake coins.
If the magnet is too strong, it may pick up both.
Obviously the intent here was to deceive by passing for real.
And since they were made in large quantities, that's what they did until caught.
So I guess my point is that the couterfeiter may just decide, what is available, what may sell.
Maybe some coins are so expensive to fake that buyers & graders would use close scrutiny.
Others of lower cost may sometimes be sold between dealers and collectors but nobody really studies the coin if it looks good in hand and weighs good.
I have some fakes that are impossible to detect in hand with the eye.
It takes a microscope and testing to tell them apart from the genuine coins.
Not done very much at a coin show.

The higher silver content is the result of silver surface enrichment. Silver and copper alloys particularly for Ag alloys that exhibit 90% Ag in their original alloy mix do indeed register silver levels ~ 95% after some decades of environmental exposure where a thin film of enriched silver forms at the surface. See the classic paper by L. Beck on silver surface enrichment. Its a bit complex but this is a common XRF result where Ag is reading HIGHER than the original alloy mix (i.e., 90%). Its genuine IMO. Remembering XRF analysis is restricted to a VERY thin layer at the surface measured at best in tens of microns in width. John Lorenzo (Numismatist).

Silver surface enrichment of silver-copper alloys: a limitation for the analysis of ancient silver coins by surface techniques

Lucile Beck

FABIEN PILON
2004, Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms