Home Jade & Gems Gemology A Star Is Born

A Star Is Born


A Star Ruby With Excellent 6-Ray Star At Its Dome

Asterism is the effect of a six-ray or four-ray star on top of a dome of a cabochon gemstones.

A Beautiful 6-Ray Star Sapphire Set With Ascending Diamonds

Fine Silk Inclusion Of A Star Ruby Intersecting At 60 degree

In effect, asterism is the same as chatoyancy (Read here for Phenomenon Gems), except that there are 3 sets of fine parallel fibers lying along the same lateral axes and intersecting at 60 degrees to each other.

In the Burmese rubies these fine parallel fibers are the silky inclusions which fluorescence crimson red under UV light.

Prominent Silk Inclusion In A Burmese Sapphire

The most prominent of the 6-Ray Star effect is found in Corundum (Read here for Corundum).  The beautiful star in Rubies and Sapphires are much sought after by gems and jewelry connoisseurs.

A Ruby In The Rough, Notice The Hexagonal Shape

I have cut some star rubies in Myanmar before being taught by a gemstones cutter.  We used some oil to rub on the surface of a rough ruby.  The stone is to be rotated until you find a fuzzy star on one of the rough surface.  This should be the apex of the dome of the star.  It is easy to find it but to really cut out an excellent star effect from a corundum you need to have varied experiences for the rough is very expensive.

The 4-Ray Star Diopside

Star Diopside, a black gemstone, is relatively unknown to the public, has a unique 4-Ray star which is created by platelets of magnetite instead of parallel intersecting needles.

The 6-Ray Star Rose Quartz

Rose quartz which crystallizes in the hexagonal system also has a 6-ray Star effect.  However, asterism in Rose Quartz is visible in transmitted light rather than reflected light.

There will be another post later on how to evaluate the quality of a star on a ruby/sapphire.

Sources & Citations

http://www.palagems.com, http://www.star-sapphires.com, http://www.stargemstones.com, http://gemsbydeni.com, http://www.thaigem.com/, http://www.thenaturalsapphirecompany.com

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I am a Graduate Gemologist trained at the Gemological Institute of America (GIA) in New York City, USA. I hold an MBA degree from Cranfield University, United Kingdom, and a Bachelor degree in Mathematics. My earlier profession was a banker until I found jade in Myanmar (Burma) in the early 90s. I have traveled to the fabled Hpakan Jade mines, and Mogok, the world’s famous rubies and sapphires mines in upper Burma, with my second son. Three of my children are also Graduate Gemologist, GIA, NYC and they deal in diamonds, gemstones and jade. 我是在美国纽约市的美国宝石学院(GIA)接受过培训的宝石研究学家。 我拥有英国克兰菲尔德大学的工商管理硕士学位和数学学士学位。我以前的职业是银行家,直到90年代初我在缅甸接触到玉石。我曾经和我的次子一起去过缅甸上流传说中的哈帕翡翠矿山和莫谷矿山, 莫谷矿山是世界上著名的红宝石和蓝宝石矿山。我的三个孩子都是纽约市GIA毕业的宝石研究学家, 他们专门处理钻石,宝石和玉石.


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