Question

In ruby and emerald, the metal ion(s) present is/are:

• A. \( \text{Cr}^{6+}, \text{Mn}^{3+} \)
• B. \( \text{Cr}^{3+} \)
• C. \( \text{Mn}^{3+}, \text{Co}^{3+} \)
• D. \( \text{Co}^{3+} \)

Hint:

Cr\(^{3+} \) imparts red color in ruby and green in emerald via d-d transitions.

Answer 1

The Correct Option is B

- Ruby: Red color comes from \( \text{Cr}^{3+} \) ions doped in aluminum oxide \( \text{Al}_2\text{O}_3 \)
- Emerald: Green color due to \( \text{Cr}^{3+} \) ions in beryllium aluminum silicate
So in both gemstones, the active coloring species is \( \text{Cr}^{3+} \)