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Iridescent Andradite
Gem Profile

You've heard of the Mohs scale, that 1-to-10 series of rankings for the hardness of each gem. Ah, but have you heard of the Meg's scale, that 1-to-10 series of rankings for the lapidary challenges posed by each and every gem?

Don't scold yourself for not knowing about this ratings system. It's the exclusive creation of Meg Berry, a cutter based in Fallbrook, California. "Meg's Challenge Scale," as she calls it, is a device she uses to communicate the difficulties and length of time it takes to master a new gem.

Since 2003, she has been working on developing a full understanding of iridescent andradite, a new garnet found mostly in Mexico. Although she finds it one of the most beautiful gems she has ever worked with, Berry has assigned it possibly the highest rating ever on her challenge scale: 8+. That's even greater than what Berry describes as the stone's "high-seven hardness."

Don't get the wrong idea. Berry uses the word "challenge" to talk about the mysteriesórather than frustrationsóposed by a new gem. It is a term of endearment. For the few cutters so far entrusted with it, iridescent andradite looked to be one way and proved to be another. "I've still got loads to learn about this gem," Berry says.

Iridescent andradite is the first garnet that must be considered a phenomenon stone pure and simple. Indeed, if it were not for its opal-like color play, it would be, says Berry, "only worthy of use in fish tanks and gardens." Instead, it can give fine opal a run for the money.


At first, and even second, glance, iridescent garnet could be mistaken for opal, ammolite, or fire quartz. Even Berry, who is used to examining gems for crystallographic clues to their identity, says she would never have guessed the new andradite as garnet. "Garnet is not a gem family known for phenomenon stones," she says.

Garnet is a large, complex gem family with many distinct branches and lots of interminglings. You've got pyrope, almandine, spessartite, grossular, andradite, and mixed breeds like Malaya which is part pyrope and part spessartite, and pyrandine which is part pyrope and part almandine. Among garnets, andradite is synonymous with rarity. Until now, andradite's reputation rested almost solely on demantoid, a lively life-saver green variety discovered in the Ural Mountains in 1868. In homage to its high dispersion, it was given a variety word taken from the Dutch word for diamond.

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