France 500 francs 1994 Pierre et Marie Curie

Hello
Can anyone tell me why this banknote has gold letters visible to the naked eye? They usually appear with ultraviolet rays.

Thanks

I also want to know why that shows up.

I have a P prefix where it doesn't show and banknote.db has a C prefix that doesn't show under ordinary light:

500 Francs 1995 - France - BanknoteDB.com

Does that gold radium symbol fluoresce also?

Under UVA it should be bright green and under UVC it should turn red.

500 Francs - Pierre & Marie Curie (type 1993) - France – Numista

With UVA I don't know the color, I don't have a UVA device, but to the naked eye it is fluorescent.

Can anyone tell me why this banknote has gold letters visible to the naked eye?

Likely a stamp (post production).

I don't think so, because the radium symbol appears on all banknotes with UV activity, and I think it would be very difficult to put a stamp in exactly the same place.

It's a shame you don't have a UV light, you could have more info.

I adjusted your image in Photoshop:

Then I toggled that part with the UV image of a similar note on banknotedb.com:

To me it looks like your brown Radium symbol is the UV ink symbol, maybe degraded so that it now shows under white light. 

That's just a guess though. I don't know if that is possible.

If it was mine I would definitely look at it under UV.