18th Century 6 Pence And 19th Century Farthing Grade?

From the sharpness perspective both coins would fall in the EF-AU category using U.S. terminology. The farthing may have scratches on the portrait or they might be a holder if the picture of the piece was taken while it was in one. If the scratches are on the coin that is a minus.

Unfortunately both pieces have been cleaned with an abrasive. If the situation is worse for the copper coin than the silver piece because copper coins almost never should be dipped or cleaned. The silver piece appears to have a lot of small scratches or hairlines from the cleaning. As such these coins would not get a straight grade from a third party authenticator.

For placing a market value, think in terms of Fine or VF for pricing. Both would have been nice coins if they had not been cleaned.