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### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# A ring with a colorless gemstone is dropped into water. The gemstone becomes invisible when submerged. Can it be a diamond? Explain.

When the gemstone's index of refraction is the same as, or close to, that of the surrounding water, it becomes invisible. Because diamond has a particularly high index of refraction, it can still sparkle as a result of total internal reflection, but it is not transparent.

Hence, the gemstone is not a diamond.

See the step by step solution

## Step 1: Definition of gemstone

A gemstone is a mineral crystal that has been cut and polished and is used to create jewelry or other adornments. However, certain rocks and, on occasion, organic materials that are not minerals are also used for jewelry and, as a result, are frequently considered gemstones.

## Step 2: Explanation

Since the gemstone became invisible after being submerged in water, this means that light incident through water and traversing through the gemstone does not experience any light refraction; thus, it is invisible. In other words, the gemstone and the water have the same optical density, and thus you cannot distinguish between them (thus, the gemstone is invisible to your eyes).

This means that because light does not refract through the gemstone, it has the same refractive index as water. Since the refractive index of water is 1.333 and the refractive index of the diamond averages at 2.43, the gemstone cannot be a diamond.