How to save and load Color3Values to Datastore using JSON?

You can't technically "save a Color3" but you can save the RGB values. According to the Roblox wiki Color3s have three values... R G and B. R is red, G is green, B is blue.

To recreate a Color3 from it's red, green, and blue colors you can use Color3.fromRGB or Color3.new and divide your RGB values by 255 to get a decimal.

Wiki page: http://wiki.roblox.com/index.php?title=API:Color3

Example table to save:

{R=color3.R, G=color.G, B=color3.B}

You can save the RGB value simply with a datastore - I will reference this wiki throughout my explanation.

--In a script in ServerScriptService. Data stores are SERVER ONLY!

local DataStoreService = game:GetService("DataStoreService")
local RGBdata= DataStoreService:GetDataStore("RGB")
local a = 5   -- Insert first RGB color
local b = 10   -- Insert second RGB color
local c = 50   -- Insert third RGB color
local savetable = {a, b, c}

local function onPlayerAdded(player)
    local newdata = RGBdata:GetAsync(player)
    --This is your RGB that you saved in the data store.
end

game.Players.PlayerAdded:Connect(onPlayerAdded)
game.Players.PlayerRemoving:connect(function(player)
    RGBData:SetAsync(player, savetable)
end)

What you are doing, is when the player joins your game you simply get a sync from the data store. When the player leaves you do the opposite. Let me know if you have any additional questions.

You can use the functions HttpService:JSONEncode when saving the data, and HttpService:JSONDecode when retrieving.

local dss = game:GetService('DataStoreServive'):GetDataStore('Example')
local http = game:FindService('HttpService')

function save(key, value)
       value = http:JSONEncode(value)
       local success, message = pcall(function()
               dss:SetAsync(key, value)
       end)
      return success, message
end

function retrieve(key)
       return http:JSONDecode(dss:GetAsync(key)) or nil
end

-- Simple usage

game.Players.ChildAdded:Connect(function(player)
       local data = retrieve('user_'..player.UserId)
       print(data)
end)

game.Players.ChildRemoved:Connect(function(player)
       local s, m = save('user_'..player.UserId, Color3.new(255/255,0,0))
       if s then
              print('Success')
       else
              print('Failure: '..m)
       end
end)

I found this youtube video helpful. At the beginning it is a bit slow and confusing but once you get through the video you should be able to do what you are trying to do. Here is the link. Hope it helps!