Level 1 is the darkest level of hair color--dark black.
Black shades are either Level 1, Level 2, or Level 3, and Level 1 is the darkest. Level 1 is primarily unnatural--even people whose natural hair colors are black do not naturally have Level 1 black hair. Refer to the chart of hair color levels.
Level 1 hair color is usually found in blue black hair colors or "ultimate" black hair colors. It is best suited for people whose natural hair color is from Level 2 to Level 3. While Level 1 color often has neutral or no undertones, the overall effect is "cool" as opposed to neutral or warm.
All the Level 1 hair color shades can be found in the category "dark blacks".