How to make a meshpart change 1 color to another then go back and so forth?

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#1

I want to make my crystals (Vertex Colored) to change from “Institutional white” Color to “Ghost Grey” then go back to “Institutional White” color and then ghost grey again and so on, how would I achieve that? (I’m trying to make a glowing effect.)
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#2

Can’t you use TweenService?

local crystal = script.Parent --assuming the script is inside of the crystal
local tweenservice = game:GetService("TweenService") 
local glowcolor = Vector3.new(1,1,1) 
local glowtime = 0.25
local tweeninfo = TweenInfo.new(glowtime, Enum.EasingStyle.Linear, Enum.EasingDirection.Out, math.huge, true, 0)
tweenservice:Create(crystal,tweeninfo, {VertexColor = white}):Play()
#3

oh yeah I didn’t realize about that sorry.