May 21, 2024
The Science of Sparkle How Gemstones Get Their Shine

Gemstones have been captivating humanity for millennia, with their alluring beauty and radiant gleam. Whether it’s the deep red of a ruby, the clear brilliance of a diamond, or the subtle shimmer of an opal, these precious stones never fail to capture our imaginations. But have you ever wondered what’s behind the sparkle? What makes gemstones shine so uniquely?

Why Do Gemstones Sparkle?

To understand the shimmer and glint of gemstones, we first need to dive into some basic principles of optics and mineralogy. At its core, the brilliance of a gemstone is all about how it interacts with light.

1. Refraction:

  • When light enters a gemstone, it slows down and bends – this phenomenon is known as refraction.
  • The degree to which light refracts inside a gemstone is measured using the refractive index. Gemstones with a higher refractive index will typically appear more brilliant as they bend light more.
  • The variance in the refractive index among different gemstones contributes to their distinctive levels of sparkle. For instance, a diamond’s high refractive index is one of the reasons behind its exceptional brilliance.

2. Internal Reflection:

  • After light is refracted within the gemstone, it often reflects off the internal facets (or surfaces) of the stone.
  • A gemstone cut in a particular shape, such as the classic round brilliant cut for diamonds, is designed to maximize this internal reflection, ensuring that most of the light that enters the stone is reflected back out to the viewer’s eye.

3. Dispersion:

  • As white light travels through a gemstone, it can split into its constituent colors – a phenomenon known as dispersion.
  • This causes the beautiful play-of-color seen in some gemstones. Think of the rainbow-like fire inside a well-cut diamond or the spectrum of colors in an opal.

Factors Influencing the Shine

While the interaction with light is central to a gemstone’s sparkle, other factors can significantly influence its shine.

1. Clarity:

  • Gemstones with fewer internal or external flaws (inclusions) tend to sparkle more since there’s less interference with the passage of light.
  • In diamonds, for instance, clarity grades range from Flawless (no inclusions or blemishes visible under 10x magnification) to Included (inclusions and/or blemishes visible to the naked eye).

2. Cut:

  • The way Evry Jewels’ gemstone is cut and faceted plays a pivotal role in determining its shine.
  • A well-cut gemstone will have facets that are precisely angled and sized to optimize the internal reflection of light. In contrast, a poorly cut stone may appear dull due to light leaking out of the bottom or sides.

3. Polishing:

  • A polished gemstone will reflect more light from its surface, contributing to its overall sparkle.
  • Proper polishing removes any surface imperfections, ensuring a smooth and reflective finish.

4. Type of Gemstone:

  • Not all gemstones shine the same way. While diamonds are renowned for their fiery brilliance, other stones like moonstones or opals are loved for their adularescence and play-of-color, respectively.
  • Different minerals have distinct optical properties. For instance, garnets can have a refractive index ranging from 1.72 to 1.94, depending on the type of garnet.

Enhancing the Sparkle

Once you’re familiar with the natural factors influencing a gemstone’s sparkle, you might wonder: can we enhance it? Indeed, throughout history, gemologists and artisans have developed techniques to amplify the natural brilliance of gemstones.

1. Setting:

  • The type of metal and setting used can either complement or hinder a gemstone’s natural sparkle.
  • For example, diamonds set in white gold or platinum can appear even more brilliant because the reflective properties of these metals enhance the diamond’s natural shine.

2. Coatings:

  • Some gemstones, especially those used in costume jewelry, may be coated with a thin layer of a shimmering substance to enhance their shine.
  • However, these coatings can wear off over time and may not be present in high-quality gemstones.

3. Treatments:

  • Various treatments, like heating or oiling, can improve the clarity or color of gemstones, indirectly boosting their sparkle.
  • Consumers should always be informed about any treatments a gemstone has undergone, as it can affect the stone’s value and care requirements.


In conclusion, the mesmerizing sparkle of gemstones results from a combination of their innate optical properties, external factors, and, at times, human intervention. The next time you’re enchanted by the shimmer of a gemstone, you’ll know the beautiful science behind that sparkle.

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