What is one of the charms of gemstones, “color change effect” and “pleochroism”?

"Color change effect"

The discoloration effect of gemstones has other names such as "color change effect" and "Alexandrite effect". This is a phenomenon in which the color and brilliance of a gemstone changes depending on the type of light and the surrounding lighting environment, and gemstones with these characteristics are also called ``color-changing stones'' and are very popular.


The pleochroism of gemstones refers to the property that their colors appear to change when viewed from different angles, regardless of the light source, and is one of the important elements that makes gemstones look more beautiful and attractive.

In particular, gemstones with strong pleochroism have many passionate enthusiasts.

Typical gemstones that have a “color-changing effect”

Synonymous with color-changing effects, alexandrite changes from green under natural light to reddish-purple under incandescent light. It is considered the birthstone for June and is known as a stone that brings health and happiness.

・Color change garnet
Color-change garnets appear gray or brownish-green under natural light, but under incandescent light they change color and may even appear red or purple.
Color change garnet is also known as one of the rarest types of garnet, which is the birthstone for January.

・Color change sapphire
Color-change sapphires are blue or purple under natural light, but may also appear green or pink under incandescent light, and the color varies depending on the region of origin.
Color change sapphire is one of the rarest varieties of sapphire, the birthstone for September, and those from Cacharai, Brazil, are considered extremely valuable.

・Color change amethyst
Color Change Amethyst is usually purple in color, but can also appear red or pink under incandescent light. Color change amethyst, like color change garnet and sapphire, is known as one of the rarest types of amethyst, which is the birthstone for February.

Typical gemstones with pleochroism

・Tanzanite Tanzanite is a pleochroic gemstone whose color changes mainly from blue to purple. When it comes to gemstones that are ``pleochroic'', the first thing that comes to mind is tanzanite.

Iolite is a gemstone with crystals that vary in color from blue-purple to yellow-brown, and three colors tend to be commonly seen: near-purple blue, pale blue, and grayish yellow.
It is also said to have effects such as stabilizing the mind and improving concentration, and is popular as a healing stone.

・Oregon Sunstone
Oregon Sunstone is a gemstone primarily found in Oregon, USA.
As the name suggests, most of them have a pale orange color, as if they were trapped in the sun, but some are a little rarer and have pleochroic properties that change the color to green, yellow, or red depending on the angle. can be seen.

Apatite is a gemstone with an extremely rich variety of colors that develops various colors depending on the ingredients it contains, but it is said that all of them are pleochroic regardless of their hue.
Additionally, apatite that has a color-changing effect has been produced, although it is extremely rare.

What's wrong? Color change effect and pleochroism

Color change and pleochroism, which are often confused because their names are similar, have the same thing in that they change the appearance of a gemstone, but their causes and characteristics are completely different.

Pleochroism occurs because the refractive index differs depending on the direction of the gemstone's crystals, which causes differences in the absorption and transmission of light, resulting in changes in the colors that humans can see. For example, amethyst can appear in multiple colors, such as purple, pink, and blue, depending on the viewing angle due to the crystals inside it.

On the other hand, the color change effect is a phenomenon in which the color and brilliance of a gem changes depending on the type of light, angle, and surrounding lighting environment, and does not depend on the crystals inside. A typical example is the aforementioned alexandrite, which shows different colors under natural and artificial light sources.

Unique gemstones with color-changing and pleochroic properties that allow you to enjoy a variety of expressions with just one loose piece.
Please find your own favorite.

*Please note that this translation is provided for informational purposes, and for any legal purposes or concerns, the original text in Japanese should be consulted.