Gemstone Spotlight: Prasiolite

Gemstone Spotlight Prasiolite
by: Ben Tseytlin - on Antiques & Jewelry

Prasiolite gems are greenish yellow in color and are a variety of quartz which can be cut into stones that are faceted for usage in jewelry. It is processed in three different ways, which are irradiation, heat treatment and natural heating.

Where Does Prasiolite Come From?

There are only a few places in the world where the amethyst will transform into Prasiolite after heating. The majority of the gems which are found on the market today come from the Brazilian Montezuma deposit at Minas Gerais, while some deposits have also been found in the U.S. state of Arizona and still others have been found in Poland which upon irradiation will transform into Prasiolite.

Although Prasiolite is best known for its greenish color, it can also appear in other colors such as purple. Its coloration is the result of the iron which is present within the quarts. Although the color is stable in most cases, if the stone is subjected to sufficiently high temperatures the color will change. For instance, when amethyst is subjected to temperatures of 470 Celsius degrees they will become yellow, and at 550 degrees may become brownish red. The gems may then be sold in the form of citrine which has been heated treated. While Prasiolite can appear in multiple colors, the majority of people prefer green over purple, yellow, or reddish brown.

Prasiolite Characteristics 

The Moh’s hardness scale for Prasiolite is 7 and it doesn’t have any cleavage. This stone is quite durable, with wearing properties which are similar to citrine, rose quartz of amethyst. As a result it is an outstanding gem for jewelry, whether it is earrings, pendants, rings, bracelets or more. The majority of the Prasiolite sold on the market has light saturation and color. The smaller stones won’t display much color since their saturation is very light. The stones which display the famous green color are usually small.

When Prasiolite is heat treated, it will be subjected to temperatures of five hundred degrees Celsius. This temperature will alter the color, transforming it from purple into green. When irradiated Prasiolite will result from natural amethyst, and will usually have a color which is light green. However, this greenish coloration is unstable and might fade unless it is subjected to temperatures in excess of one hundred and fifty degrees Celsius.

How To Wear And Care For Prasiolite

Prasiolite can be worn with a variety of attire and at various functions and occasions. It is used in numerous jewelry types but must be properly cared for to maintain its luster. If it is exposed to excessive sunlight and some forms of artificial illumination for extended periods, it will start to fade. Therefore, when not in use these gems should always be stored in cool and dark environments, such as cabinets, bags or jewelry boxes. It should not be left in hot vehicles during summer nor should it be stored near a heater or fireplace.