First get clear corn starch, red dye, blue dye, and a container.
I don't have exact messurements but cover the bottom of your container with the cornstarch and add 15- 20 drops of red dye, don't worry about it being a light color the blue will darken it.
Now add the blue dye. Do this carefully! Too much blue and it turns purple - ish.
Add bout 5 drops and mix, if its still too light add more. You want it slightly too dark, if its too light it looks really fake.
All done! Now you can drizzle or splatter it over what you want.
You can also make party props but I'll add that in another how to.