Asterism minerals are fascinating types of gemstones because when polished they display a 6-ray or 4-ray star that moves around inside the stone.
If you’re into rockhounding, you’re in for a treat! Learning about the different types of rocks and minerals is a great way to start. You can begin by using my “how to identify series.” I’ve designed this series to help beginners quickly learn how to identify the various types of rocks found in nature. It can help you to better understand the different characteristics of rocks, including color, texture, and mineral content. The helpful tips can significantly improve your rockhounding experience.
In addition, rock and mineral shows are another great way to find high-value specimens and learn more about geology! Many of these shows are held locally and often feature educational activities. You can even find affordable deals on various gemstones.
If you’re looking for a local rock and mineral club, I suggest checking out our “explore by state” page. You should be able to locate your state and the corresponding clubs there.
Names of Asterism Rocks
Gemstones that display asterism are not abundant but some types can be acquired fairly easily. The one’s on the higher end like, star ruby and star sapphire, can demand a high price per carat depending on color and a sharp 6-ray star.
Here are some of my favorite star gemstones and I hope you add a couple of these to your collection.
Star ruby is one of the most sought-after asterism minerals in the world. It is a variety of corundum and is well-known for its deep red color and 6-ray star. High-quality stones are found in smaller to medium-sized cabochons while lower quality can be found in medium to large-sized stones. The differentiator is the quality of the 6-ray star.
Star ruby exhibits a six-rayed star pattern with three parallel fibers when viewed under a single light source. It is typically found in various parts of the world, including the U.S.A., India, Madagascar, Thailand, and some parts of Africa.
- Mohs hardness: 9
- Specific gravity: 4
- Refractive index: 1.76 -1.78
- Glassy (vitreous) luster
Star sapphire is another type of star gemstone known for its beautiful star-shaped pattern. It is usually a deep blue color and is composed of a mix of corundum and rutile, which gives the stone its distinctive appearance.
Star sapphires are predominantly found in Sri Lanka, but you can still find them in Australia, Burma, Thailand, US.A, and Africa.
The most valuable star sapphires are those with a deep blue color and a sharp, well-defined star pattern.
- Mohs hardness: 9
- Specific gravity: 3.9 – 4.1
- Refractive index: 1.76 -1.78
Star garnets are a variety of almandine and can be found in colors ranging from a deep red with a hint of purple or deep purple with a touch of red. The most common variety comes from Idaho and can be found at most rock and mineral shows. They’re an excellent choice if you’re looking for something that can stand out and make a bold statement in any collection.
- Mohs hardness: 7.5
- Vitreous luster
- Refractive index:1.72 -1.94
- Specific gravity: 3.2- 4.3
- Can be used as an abrasive
Star Rose Quartz
Star rose quartz is known for its lovely soft pink hue but did you know you can find pieces displaying a 6-ray star? When the right piece of rose quartz is orientated correctly and accurately cut, it will display a beautiful 6-ray star.
The higher quality material is mined in Madagascar and the darker-colored stones show the asterism best. Make sure to keep your eye out for high-quality pieces while attending your upcoming rock and mineral show.
- Mohs hardness: 7
- Specific gravity: 2.65
- Refractive index: 1.544 – 1.55
- Used as art and display piece
Black diopside, or Indian black star diopside, is unique because of the number of rays on the star. The stone is made from calcium magnesium silicate and features a white four-pointed star.
Featuring a deep, lustrous black color, black diopside is genuinely a work of art. It is a type of pyroxene mineral from India and is mined from various locations worldwide. It can be found in the Ural Mountains of Russia, Canada, and some parts of the United States.
When polished, black diopside has a brilliant luster and can be cut into various shapes.
- Mohs hardness: 5.5
- Specific gravity: 3.22 – 3.38
- Refractive index: 1.66 – 1.73
Common and Rare Asterism Minerals
Star gemstones are fascinating. Not only do they have an eye-catching and unique appearance, but they also have a long and interesting history. From star ruby to star garnet and black diopside, asterism minerals can make a great addition to any rock collection.
Asterism rocks are a great option to consider whether you are a collector or a jewelry maker. They come in various shapes, sizes, and colors, making them perfect for jewelry creations or standalone pieces.