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Find a sapphire with an asterism. Obtain a sapphire from a shop that offers certification. Buy a synthetic sapphire.

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In most cases, inclusions are not desirable, and sapphires containing many inclusions might be considered of low quality.  However, sapphires containing an asterism -- a naturally occurring arrangement of inclusions into a six-pointed star shape -- are rare and considered valuable. Gemological societies (for instance, the Gemological Institute of America or the Gemological Association of Great Britain) offer certification to trusted gem dealers.  The certification should verify the claims that the dealer or jeweler makes about the sapphire, including where it comes from and how much it weighs.  Getting a certified sapphire is especially important if you’re purchasing an expensive one. Some sapphires are found not in mines, but made in laboratories.  These synthetic sapphires are of much higher quality (and far more affordable) than natural ones, so choose synthetic sapphires whenever possible. Generally, synthetic sapphires have fewer inclusions, greater clarity, and more brilliance than natural gemstones.