help needed with Argentina earies

Hello everybody,
I am hoping there is someone more knowlagable than myself with early Argentina.
I no longer collect these and I am hoping to sell the via a club packet,but first I need to identify them correctly and verify if they are genuine.
the first is 1864 what I think is sg14,I cant remember were I aquired this stamp from but it has a cat. value of£1300 which makes me suspicious,it does have the "RA" watermark

 

here is another,
sg15 allegedly cat val of £4500 it is also watermarked,cancell looks suspect.?
the 5centavos red I think is sg13 is watermarked.
the 10 centavos green perf 11.5 I think is sg17.
final image I believe is sg24,1867 no wmk, I realise that most of you chaps don't use Gibbons

 

It is nearly impossible to judge from a scan.
But to me it looks like,that your stamp is not engraved,but litho-printed.
If so,it would be a wellknown forgery.These exist with and without watermark.
But again,it is very difficult to see the printing method on a scan.