The Origins of Color in Colored Gemstones-- Decoding the Mystery

The Origins of Color in Colored Gemstones– Decoding the Mystery

It’s amazing how the Earth created a wide variety of colored gemstones, but what makes their colors so bright and unique?

  1. Formation of gemstones
  2. Causes of Gemstone Color
  3. How to enhance the color of colored gemstones

Formation of gemstones

Most gemstones are formed deep underground, where molten minerals cool and solidify under intense pressure—a process that takes thousands of years. The minerals are then removed through volcanic or tectonic activity over the course of thousands of years. Forced to move toward the surface.

Some gem-quality minerals, including quartz, corundum, diamond, and beryl, are transparent in their purest states. These minerals tend to have simple crystal structures with no impurities or inclusions.

Causes of Gemstone Color

But as we know, gemstones and diamonds can appear in all colors under the sun because of various chemical impurities present in their atomic structure.

The chemicals that produce color in gemstones are introduced below:

  • Nitrogen – The presence of nitrogen can cause gemstones and diamonds to appear yellow or brown, and in some cases, depending on concentration and distribution, pink or purple.
  • Boron – The presence of boron can give gemstones a blue or purple color.
  • Chromium – The presence of chromium can make rubies and sapphires appear red or pink.
  • Iron – The presence of iron can turn the gemstone yellow, orange, brown or green.
  • Copper – The presence of copper gives gemstones, such as turquoise and Paraiba tourmaline, their blue or green appearance.
  • Titanium – Gemstones such as sapphire will appear yellow, orange or pink if they contain titanium.
  • Manganese – Impurities in manganese can cause gemstones such as spinel and molybdenum ores to appear pink or purple.
  • Iron and Titanium – In the case of sapphire, the blue color is caused by the presence of iron and titanium impurities in the stone’s crystal structure. These impurities absorb certain wavelengths of light, making the gem appear blue to the human eye.
  • Chromium or Vanadium – The green color of emeralds is caused by the presence of trace amounts of chromium and/or vanadium

The color of a gemstone depends on the type and concentration of chemicals, as well as the size and shape of the gemstone. In the case of colored gemstones, highly saturated colors are often valued over subtle hues.

Sometimes the mineral will have more than one chemical inside it. Resulting in a multi-colored stone, a good example of this is watermelon tourmaline, which contains green, clear, and red streaks. Usually for maximum Each stone is cut to play with the three colors.

There are also many colored minerals that are opaque when formed, such as hematite, magnetite, and pyrite.

How to enhance the color of colored gemstones

It is a common practice to heat certain gemstones to enhance their color and clarity. For example, brown or yellow sapphires are often heated to remove impurities or change the stone’s crystal structure to achieve a more desirable color.

During the heat treatment process, sapphire is placed in a special oven or furnace and heated to a temperature of around 1800-2000 °C . The heat causes the molecules in the sapphire to vibrate and crack, thereby removing or rearranging unwanted brown impurities. The sapphire is then slowly cooled so that the crystal structure reorganizes in a more ideal way.

After heat treatment, brownish sapphires may appear bluer or greener in color. The exact shade of sapphire will depend on the specific impurities present in the stone as well as the temperature and duration of the heat treatment. Heat treatment is a generally accepted practice in the gem industry, but it is important to note that heated sapphire must be reported and sold as treated sapphire.N.J. Hope this article can help you understand ‘The Origins of Color in Colored Gemstones’.