HOW TO SPOT A FAKE BLUE STAR SAPPHIRE?
BLUE STAR SAPHIRE sometimes displays a three-ray, six-point star. These star sapphires are cut in a smooth domed cabochon cut to display the effect. The star is best visible when illuminated with a single light source: it moves across the stone as the light moves. This effect, called asterism, is caused by light reflecting off tiny needle like rutile (called "silk") arranged in three sets of parallel needles that intersect one another at 60 angles. Star Sapphire is usually found in Blue colors, but there are also various shades of brown and green that are called Black Star Sapphire. Orange and Yellow Star Sapphires are almost unknown, and very rare. Color Changing Star Sapphires are even more of a rarity.
The value of star sapphires are influenced by at least these two things: 1) the intensity and attractiveness of the body color, and 2) the strength and sharpness of the star. Of course all six legs should be fairly straight and equally prominent. Star sapphires rarely have the combination of a fine translucent or transparent color and a sharp prominent star, but when offered, these gems are highly valued and the most expensive. There are not very many chemicals that could attack this gem, but if boiled in a diamond cleaning kit the stone can lose it's polish, also Jewelers pickling solutions containing boron will etch the surface.
TREATMENTS - Genuine Star Sapphire is not typically treated with 'heat' or any other treatment to enhance the color or alter the clarity. If a Star Sapphire were to be heated the person doing the heating seriously risks dissolving the rutile needles that cause the asterism to form a star
CARE - It is risky to clean Star Sapphire in an Ultrasonic Cleaner, and risky to use a steamer. We strongly recommend Ionic Cleaners and/or warm, soapy water and a soft brush as the best way to clean Star Sapphire jewelry.
HOW TO SPOT A FAKE! - Most commonly you will see that synthetics jump out as way too perfect looking, ie: a perfect star, a super clean stone, and great color. If you own one and aren't sure if it's genuine... Here's a few quick ways you might be able to tell the difference... First thing to look at is the bottom, if there is an "L" stamped in the stone, it's a Lindy Star and synthetic... if it does not have an "L" it passes that test, so now look for imperfections within the stone, and/or unevenness on the bottom, and/or stripes or lines of color that shows through the top. Almost all natural Star Sapphires have one or more of these natural imperfections. Then look at the star itself, using a flashlight... most natural stars do not have a "perfect" star... the natural will most likely have 1 or more of the 6 legs not exactly the same length, or maybe not all 6 are perfectly straight. Now move the flashlight around in a circle, the genuine star will travel around and follow the light source. If the star stays stationary it is definitely synthetic. It would be helpful if you can look at the bottom of the gem, synthetics are always on the bottom, and usually have a very low dome, whereas the natural star typically will have an uneven bottom that may even have chunks of stone that appear to be missing, or dark spots on the lower portion of the gem. If it passes these tests, I recommend you take it to a jeweler that has a thermal conductivity gem tester (this tester has a needle gauge, not just the diamond tester that just makes a beep) and ask him to test the stone with this instrument, the dial should jump to the mark just before a diamond to tell you it's corundum. If it passes this test you may have a genuine Star, but don't get super excited yet, these are just simple things you can do to rule out the majority of synthetics, the only way to be sure is to send the stone to a certified reputable Gemologist and ask for a Gem Identification Report.
Example of a synthetic blue star sapphire in a sterling silver ring
If the pictures you see on eBay Listings are too good to be true. Most likely you have spotted a fake/synthetic Blue Star Sapphire!
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