The 20-year-old arrived at Vicarage Road in the summer from Fluminense for a fee of £11.5m and he has made an immediate impact at the Hornets.
His equaliser in stoppage time during Saturday's 2-2 drraw at West Brom was his third Premier League goal, scoring a vital late goal for the second consecutive game after grabbing the winner at Swansea.
"He is a fantastic boy, an amazing talent," Silva said. "From the first day I arrived I said to the board that I want him, because I believe a lot in this player.
"You never know how he will react because this is another country, but everything he has done until now is amazing," he added. "His skills coming into the Premier League are very good."
Richarlison's header secured a deserved comeback for Watford in the fifth minute of added time, after West Brom took an early 2-goal lead, which was reduced by Abdoulaye Doucoure in the first half.