Trail Fade Effect

I have a trail script where a player can customise the trail with whatever color they want. The feature works but the fade effect does not:

local midColor = Color3.fromHSV(0, 0, 0.215686)
local endColor = Color3.fromHSV(0, 0, 0.516536)

tr.Color ={, colr.Value),, midColor),, endColor) })

I want the trail to have a fade effect where the color becomes darker, I tried lowering the HSV value but it gives me a gray and black color and not a darker shade of the current color. Any other methods?

yea does anyone have an answer to this?