Because the color originates from the iron in them, colors fade in the sun. Ametrine-The color will fade if exposed to direct sunlight over an extended period of time. Apophyllite: In the sun, it can become brittle and the color can fade. Aquamarine: If exposed to direct sunshine for an extended period of time, the blue will fade to white. Aragonite: If exposed to direct sunlight, it may turn yellow or orange.
The temperature of the sun's surface is around 5,700 degrees. The sun emits blue light, but it also emits red and other hues with about equal strength. White light is produced by combining all of the hues. As the temperature drops, the peak shifts to the right and the sun turns crimson. If the darkness is complete, then black is visible.
Flames that are red or orange are gases that are free-burning chemicals called hydrocarbons. They are only elements that are combined together to form compounds. For example, gasoline consists of carbon, hydrogen, and oxygen. The flame of a gas lamp is usually red because it contains many more carbon atoms than oxygen atoms. A blue flame would indicate that there is an excess of oxygen over carbon, which is not possible because air has exactly the right amount of both.
The sun produces energy in the form of heat and light. It does not produce any chemical substances such as oxygen or fuel molecules. However, some chemical reactions do take place on its surface that transform part of its mass into internal energy. These reactions produce oxygen molecules that rise toward the sun's atmosphere where they are lost (because there is no place for them to go), and carbon dioxide molecules that fall back to the sun's surface. In this way, enough oxygen is kept available for use again as fuel later when another molecule falls onto the sun's surface. This process keeps going day after day and year after year, so the sun remains bright and hot.
In the sun, calcite can discolor and become brittle. Celestite: In the light, the blue will become white and become brittle, perhaps shattering. Chrysoprase is a green chalcedony of the quartz family that can fade or become brittle and break. In the sun, opal loses its color.
If you expose your amethyst to direct sunlight or other UV sources for an extended period of time, the color will fade. If you expose amethyst to heat, the color will fade as well. Sometimes, instead of gray or transparent crystal, you'll get bright yellows that resemble citrine. This is called "citrinization". While this change is not harmful, it is not desirable as it reduces the value of the stone.
Amethysts are very stable crystals that can be exposed to light and heat without any adverse effects such as color fading or loss of shape. However, due to their exquisite beauty, amethysts are valuable jewels that should be kept out of direct sunlight to prevent degradation of the surface texture.
It is possible to wear amethysts as jewelry. The stones should be cleaned regularly with a soft toothbrush to remove dust particles that may otherwise become embedded in the surface over time. Amethysts are very resistant to stains so they can be worn daily without any problems of staining or wearing off of the color.
Amethysts are sometimes referred to as "the moonstone", because of its similar color and gem quality. However, unlike the moon, amethysts are a mineral and not a metal. They also tend to be more expensive than silver moonstones.
Crystals That Shouldn't Be Exposed to the Sun
Clear Quartz: Can only be exposed to the sun for around 2 hours. After this time, it begins to darken.
Calcite is a form of calcium carbonate (CaCO3). It is found in limestone rocks and forms when algae and other organisms die and decompose under water. Calcite is the most common form of calcium carbonate in Earth's crust and atmosphere. When exposed to sunlight, calcite can develop a yellow color due to the presence of iron oxides. The amount of color varies depending on the concentration of iron oxide particles present. Brightly colored calcite may be used in jewelry or as a decorative stone in gardens.
Celestite is a form of silicon dioxide (SiO2) that occurs mainly as small clear or colorless crystals with a metallic luster. It is one of the most abundant minerals in the earth's crust. Celestite is formed when silica-rich fluids seeped out of cracks in ancient volcanoes or mountains before they could harden into rock. Over time, more and more of these fluids leaked out until only tiny bits were left.
Sunstone should not be subjected to heat, yet its color is stable and will not fade when exposed to light. This stone is used in decorative settings because of its desirable color and quality.
Rose Quartz: Color will fade in the light. Sapphire: it will lose its sapphire hue. If kept in the light for too long, the color may fade and the clusters may ignite. Topaz: Will not discolor in light.