Chromium oxide is commonly used as an ingredient in paints to achieve a green color. This is due to the characteristic green hue of chromium oxide when it is pigmented or mixed into paint. It provides a vibrant, deep green shade that is highly desired in various applications, such as artistic paintings, architectural coatings, and industrial uses.

It is important to note that chromium oxide can be used in combination with other pigments to create different shades of green. Depending on the specific formulation and concentration, the resulting green color can range from light or pale green to darker or more intense shades.

The other options mentioned in the question (blue, red, and violet) are incorrect as chromium oxide does not produce these colors on its own. Blue, red, and violet colors in paints typically come from different pigments or dyes that are specifically chosen to achieve those specific hues.

Therefore, the correct answer is option 1: green color.