You can resolve your issue by defining a list of the ggplot terms you want and add them in.
library(ggplot2) my.scale_aes <- list( scale_x_continuous(breaks = c(56, 60, 61)), scale_color_manual(values = c("black", "red")) ) diamonds[1:100,] %>% ggplot(aes(depth, price, color = cut == "Ideal")) + geom_point() + my.scale_aes