Just take it to a store and choose something close. Hopefully you can find something that will work to match what is there. I learned the hard way when I made a tiny needlepoint birth announcement. I would make them up and leave large rectangle open spots for name, birthday, weight ect. Then when the baby was born I would fill in everything. I didn't always have the same white dmc thread. It looked the same but, over time it aged different. At least it looked nice for a while. Back then I thought white was white. Now I know better.