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Grandidierite Gemstone Information

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About Grandidierite - History and Introduction

Grandidierite is magnesium aluminum borosilicate and one of the world's rarest gems. In fact, it is often listed as one of the top ten rarest gemstones and one of the most expensive stones in the world. Specimens of grandidierite are rare even in mineral collections and museums. The name, grandidierite was bestowed to the mineral in honor of Alfred Grandidier, a French explorer and geographer who thrice traversed the island of Madagascar; the place where grandidierite was first discovered in 1902 by French mineralogist, Alfred Lacroix. The beautiful greenish-blue color of grandidierite comes from the presence of iron. Transparent grandidierite specimens were pretty much unheard of until the last few years, when a new deposit was discovered in Southern Madagascar and some excitement was generated by a mere 0.29-carat faceted grandidierite gemstone from Sri Lanka. In recent years, an extremely limited number of larger grandidierite gemstones have entered the market, which judging by the past century will likely be the only stones available for a long while.

Faceted Grandidierite Gemstone

Identifying Grandidierite

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Distinguishing characteristics of grandidierite include its Mohs hardness of 7 to 7.5, its vitreous luster, characteristic greenish-blue or bluish-green color and its trichroism; the ability to exhibit three different colors depending on viewing angle. Due to the rarity and value of transparent grandidierite, it is advisable to obtain gemstone certification for any large, transparent faceted stones to confirm its identity, since it can appear similar to teal apatite or Paraiba tourmaline.

Grandidierite; Origin and Sources

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Most gemstone-quality grandidierite is mined in Madagascar, with some smaller amounts found in Sri Lanka and New Zealand. Since its discovery in 1902, very little gem-quality grandidierite was found until a new deposit was discovered in Southern Madagascar in 2014. Gem-quality grandidierite deposits are often very small and become depleted quite soon after their discovery as buyers rush to acquire samples of this rare gem. Therefore, grandidierite remains a serious collector's gemstone.

Buying and Determining Grandidierite Value

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Grandidierite Color

Grandidierite gems are typically greenish-blue, blue-green or blue, with the most highly-saturated neon color being the most valuable. Being a trichroic gem, grandidierite can display yellow, colorless, greenish-blue and blue under polarized light, depending on the viewing angle. The blue color is due to traces of iron, so specimens with more iron content have a higher saturation of blue.

Grandidierite Clarity and Luster

It was previously believed that transparent grandidierite gemstones were non-existent; and most gems are typically translucent to opaque. However, the first-known transparent grandidierite gemstone was revealed by GIA in their spring 2003 issue of "Gems & Gemology" - a 0.29-carat gemstone from Sri Lanka. Even very small transparent grandidierite gemstones are highly-valued, with opaque stones being more affordably-priced. Eye-clean grandidierite gemstones are extremely rare and can reach up to $20,000 per carat or more.

Grandidierite Cut and Shape

Opaque material is cut en cabochon and translucent grandidierite is faceted, usually with cuts that preserve carat weight, such as ovals. It is very rare to see grandidierite with another shape or cut. Grandidierite gemstones weighing 2 carats or more are extremely rare, so large faceted gems demand very high premiums.

Grandidierite Treatment

Grandidierite is not known to be treated or enhanced in any way.

Grandidierite Gemological Properties:

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Chemical Formula: (Mg,Fe2+)Al3[O|BO4|SiO4] - Magnesium aluminum borosilicate
Crystal Structure: Orthorhombic
Color: Green-Blue, Blue-Green, Blue
Hardness: 7 to 7.5 on the Mohs scale
Refractive Index: 1.590 to 1.623
Density: 2.85 to 3.01
Cleavage: Good to Perfect
Transparency: Transparent to Opaque
Double Refraction or Birefringence: 0.033
Luster: Vitreous
Fluorescence: None

Please refer to our Gemstone Glossary for details of gemology-related terms.

Grandidierite: Related or Similar Gemstones

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Kornerupine Gemstone
Kornerupine Gemstone

Grandidierite is a chemical analogue of ominelite, which is an iron aluminum borosilicate rather than magnesium aluminum borosilicate. Kornerupine is a rare magnesium aluminum borosilicate gemstone type that is chemically close in composition to grandidierite, as is dumortierite, an aluminum borate silicate mineral that is intergrown with quartz and sold as the rare gemstone, dumortierite quartz.

Gemstones that are associated with grandidierite include serendibite, quartz, sinhalite, enstatite, diopside and tourmaline.

Grandidierite Mythology, Metaphysical and Crystal Healing Properties

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Due to the rarity of grandidierite, there is little information regarding its crystal healing properties. However, blue gemstones in general are associated with faith, trust, patience and respect. In yogic philosophy, blue; particularly greenish-blue, is associated with the throat chakra, which is related to communication, expression and intuition. Therefore, gemstones with the color of grandidierite are considered to be useful for those who need to develop their self-expression skills.

Disclaimer: Metaphysical and Alternative Crystal Healing Powers and Properties are not to be taken as confirmed advice. Traditional, Ceremonial and Mythological Gemstone Lore is collected from various resources and does not represent the sole opinion of SETT Co., Ltd. This information is not to replace the advice of your doctor. Should you have any medical conditions, please see a licensed medical practitioner. GemSelect does not guarantee any claims or statements of healing or astrological birthstone powers and cannot be held liable under any circumstances.

Grandidierite Gemstone and Jewelry Design Ideas

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Since grandidierite is so rare, it is quite unheard of in jewelry. However, it is hard and durable enough to be used in any type of jewelry, if a suitable grandidierite gemstone is available. The bright greenish-blue color of grandidierite gemstones would make eye-catching jewelry, though grandidierite is more of a collector's dream than a jewelry stone. If found and intended for unique jewelry, grandidierite gemstones would not likely be available in calibrated sizes, but custom-jewelry would need to be designed around the size of the grandidierite gemstone. Anyone who owns a grandidierite ring would be lucky indeed.

Note: Buy colored gemstones by size and not by carat weight. Colored stones vary in size-to-weight ratio. Some stones are larger and others are smaller than diamonds by weight in comparison.

Grandidierite Gemstone and Jewelry Care and Cleaning

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How to Clean your GemstonesGrandidierite gemstones are quite hard and durable, so they do not require any special care. Yet, all gemstone jewelry requires proper storage and use to keep it looking good and lasting well. This is especially true for rings that are worn daily, which are exposed to more wear and tear than other jewelry items. As a precaution, always remove any grandidierite jewelry before exercising, playing sports, or engaging in household chores such as dishwashing. Store grandidierite gems away from other gems and jewelry to avoid scratches and fractures. It is best to always wrap your gemstones in soft cloth or place them inside a fabric-lined jewelry box for extra protection.

  • First Published: October-17-2017
  • Last Updated: January-17-2019
  • © 2005-2019 all rights reserved.
    Reproduction (text or graphics) without the express written consent of (SETT Company Ltd.) is strictly prohibited.
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