1803 French AV 20 Franc Genuine?

Hello everyone,

I would appreciate any advice on a new coin I have just purchased.

It is a French, First Republic 20 Franc [KM 651; F510: Numista N#24096]. Weight 6.42g, Diameter 21.0mm, Thickness 1.1mm. Die Axis 6h.

N#24096

My issues are:

1. Rim of the reverse of the coin on the right hand side particularly 2 & 4 O'clock. The rim teeth do no not appear to be struck correctly. Is this normal in a milled French coin of this period?

2. The raised areas in the field of the Obverse of the coin, in front of the face of the Emperor, on his neck and behind his neck. Also under the AR in Bonaparte. Is this normal in this period, die rust or a sign of casting?

I don't know anything about the minting of French coins and would appreciate any advice from French Coin experts. My main concern, of course: is this coin genuine? 

Thank you for your time.

I agree with your concerns, and your instinct. 

Those lumps and blobs do suggest a casting.

Are the measurements you state made by you with good instruments?

the weight seems good but the thickness is low, should be 1.25mm

hard to reconcile. 

Thank you for your reply Mr Midnight. 

Yes, my measuring instruments are quite accurate. As the coin is also reading quite high on my Sigma Metalytics Analyser  [13.5 cf 10-11 for my other 90% Au/Cu coins] I think I will get the piece XRF analysed to check it is at least made of the correct metal. The coin does have the correct specific gravity [quite a large degree of error in that calculation!], but like you, I am thinking it might be caste. I don't like the teeth on the rim. Die rust make account for the other bumps etc. It would be nice to know how fussy the French mint was during that period.

I appreciate your input. Kind regards

Michael