Final answer:
The principle of design being described is 'emphasis', which artists use to create a focal point by manipulating design elements such as color, texture, and size.
Step-by-step explanation:
Principle of Design: Emphasis
The principle of design described is emphasis, which is used to create a focal point or center of interest in artwork. Artists manipulate elements such as color, texture, shape, space, and size to achieve this effect. For example, a contrasting color can make an area stand out, like a string of gold in a dark purple field, drawing the viewer's attention directly to that spot. Emphasis helps to visually organize the elements of design and maintain the viewer's interest within a composition. Understanding how to effectively use emphasis is essential for creating captivating and visually engaging art.