Which elements are responsible for the intense red color of spinel?

The intense red color of spinel is primarily attributed to the presence of chromium and, to a lesser extent, vanadium. These elements are known for their ability to impart strong coloration to gemstones. Chromium is particularly noted for giving rise to vivid red hues in various minerals, including rubies, and it plays a similar role in enhancing the red shades of spinel.

Cobalt and iron, while they can influence the coloring of some minerals, are not typically associated with the rich red color found in red spinels. Cobalt is more commonly found in blue spinels due to its affinity for producing blue coloration, while iron can create yellow or brown hues but does not contribute to the intense red color of spinel. Hence, the most accurate elements responsible for that vibrant red color in spinel are chromium and vanadium.