How to use ggplot2 aes_string() with cut() in a for loop?

I'm trying to loop over some continuous variables to create ggplots. This works fine with aes_string, but I've now tried 1000s of variations to include cut in the call to generate bins of the variable. But it either fails or the loop does not work and it uses the same variable value within aes all the time.

In my actual data, I tried to calculate the breaks for cut beforehand similar to cut_interval(n = 6), as each variable has a different range, but this also did not help.

library(tidyverse)
data(diamonds)
diamonds <- head(diamonds, 200)

# select some numeric categories to loop over
categories <- names(diamonds)[c(1,5,6)]

# this works fine in a loop
plot_list <- list()
for (category in categories){
plot_list[[category]] <- ggplot(diamonds, aes(x = x, y = z)) +
    geom_point(data = diamonds[diamonds$color == "E", ], aes_string(fill = category), colour = "grey50", pch = 21) +
    geom_point(data = diamonds[diamonds$color != "E", ], aes_string(fill = category, colour = "price"), pch = 21)
}
plot_list

# together with cut(), it does not work anymore
cut_plot_list <- list()
for (category in categories){
  cut_plot_list[[category]] <- ggplot(diamonds, aes(x = x, y = z)) +
    geom_point(data = diamonds[diamonds$color == "E", ], aes_string(fill = cut(category, breaks = c(-Inf, 1, 10, 20, Inf)), colour = "grey50", pch = 21) +
    geom_point(data = diamonds[diamonds$color != "E", ], aes_string(fill = cut(category, breaks = c(-Inf, 1, 10, 20, Inf))), colour = "price"), pch = 21)
}
# fails: 'x' must be numeric

# this gives identical plots without fill
cut_plot_list <- list()
for (category in categories){
  cut_plot_list[[category]] <- ggplot(diamonds, aes(x = x, y = z)) +
    geom_point(data = diamonds[diamonds$color == "E", ], aes(fill = cut(get(category), breaks = c(-Inf, 1, 10, 20, Inf)), colour = "grey50", pch = 21) +
    geom_point(data = diamonds[diamonds$color != "E", ], aes(fill = cut(get(category), breaks = c(-Inf, 1, 10, 20, Inf)), colour = price), pch = 21)
}
cut_plot_list

How do I combine a for loop (or lapply) in ggplot2 with dynamic discrete values for the variable?

EDIT:

without a for loop for one variable I would call it like this:

ggplot(diamonds, aes(x = x, y = z)) +
  geom_point(data = diamonds[diamonds$color == "E", ], aes(fill = table), colour = "grey50", pch = 21) +
  geom_point(data = diamonds[diamonds$color != "E", ], aes(fill = table , colour = price), pch = 21)

# or with the binned values
ggplot(diamonds, aes(x = x, y = z)) +
  geom_point(data = diamonds[diamonds$color == "E", ], aes(fill = cut(table, breaks = c(-Inf, 1, 10, 20, Inf))), colour = "grey50", pch = 21) +
  geom_point(data = diamonds[diamonds$color != "E", ], aes(fill = cut(table, breaks = c(-Inf, 1, 10, 20, Inf)) , colour = price), pch = 21)