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The monochromatic color scheme is the use of one color. Using shades, tints and tones a harmonious room can be created that still has interest and style.
If your chosen base color is blue, then available to your design are the tints and shades of blue to create an interesting room.
Here is a sofa with a neutral base. Using pillows in tints and tones creates interest although only using one color.
If you have neutral furniture, it is easy to update the room using a monochromatic theme. In this room, a neutral base is enhanced using various colors of the chosen base color blue.