How do I make my Brick colour change to a specific RGB value?

Hi,

I have a script made for a flickering Christmas light and it changes colour every 0.5 seconds, but I've ran into an issue of limited colours.

Every time I input an RGB value into parentheses, instead of using it, it just picks the closest colour to it.

How can I solve this issue?

while true do

    script.Parent.BrickColor = BrickColor.new("Really blue")
    wait(0.5)
    script.Parent.BrickColor = BrickColor.new(89, 0, 255) -- Deep Purple type of color
    wait(0.5)

end

PS "Really blue" is the closes colour to this shade of purple Roblox studio could find.