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GemSelect Newsletter - Glorious Grandidierite

Grandidierite Gemstones

Often up there in lists of the top ten rarest gems in the world and described as a "gemstone collector's dream", grandidierite is a rare treasure that is hard to find even in museums. In 2015, an article in Forbes about "The Most Expensive Gemstones in the World" places grandidierite in third place, with a price tag of up to $20,000 per carat (please do not panic, our grandidierite gems are offered at fair prices!). For those who are curious about the top two on the most expensive gems list, taaffeite is second and red diamond is first. We at GemSelect are suitably excited to have recently acquired a rare parcel of grandidierite rough, which we have now processed into faceted grandidierite stones, along with some faceted AIGS-certified grandidierite gems and grandidierite cabochons. This is the first time that we have seen this rare gem type with our own eyes and we are delighted to be able to offer it for sale. Let's learn some more about this intriguing stone.

What's So Great About Grandidierite? Back to Top
Rare, Faceted Grandidierite Gemstone
Rare Faceted Grandidierite Gemstone

Here are some quick facts about grandidierite:

  • Grandidierite is considered one of the world's rarest gems.
  • Faceted grandidierite gemstones are incredibly rare - until around 14 years ago, grandidierite with sufficient transparency for facet cuts was unheard of.
  • Large grandidierite gemstones are extremely scarce; faceted grandidierite stones weighing 1 carat or more are exceptionally hard to find.
  • Grandidierite is not only a collector's stone, but it is also perfectly suitable for jewelry, so don't be afraid to wear it (if you can find it). With a Mohs hardness of 7 to 7.5, grandidierite is hard enough to be worn in everyday rings, but it is almost unheard of in jewelry because of its rarity.
  • Grandidierite is greenish-blue, bluish-green or blue with a gleaming vitreous luster, and can have a rare and beautiful Paraiba tourmaline-like neon greenish-blue color that is also seen in blue apatite.
  • It is a pleochroic gemstone, so at certain angles, grandidierite can appear different colors; typically blue, green or white.

Now, let's explore the history of this splendid stone.

Grandidierite Background Info Back to Top
3.99-Carat, Octagonal Faceted Grandidierite Gemstone
3.99-Carat, Octagonal Faceted Grandidierite Gemstone

The greenish-blue magnesium aluminum borosilicate known as grandidierite was discovered in Madagascar in 1902 by French mineralogist, Alfred Lacroix. Lacroix named the mineral in honor of Alfred Grandidier, a French discoverer and naturalist. Grandidier was one of the first explorers of Madagascar and visited the island in the 1860s, after which he documented his discoveries in 40 volumes. Until relatively recently, grandidierite was not seen in facetable material. However, in 2003, the first report of a transparent, faceted grandidierite gemstone from Sri Lanka excited mineral and gemstone experts, and collectors all over the world. This first transparent faceted grandidierite gem weighed a mere 0.29 carats, yet, it was an important discovery.

Take a Glimpse at Grandidierite Back to Top

A few years ago, the discovery of a grandidierite deposit in Madagascar generated great interest in the colored gemstone industry. However, the rare, gem-quality material very quickly disappeared before we could get our hands on any stones. Therefore, we consider ourselves lucky to have had the opportunity to buy some grandidierite this time and expect that it may soon disappear once again. If you are interested in rare and unusual gemstone types, feast your eyes on our grandidierite collection. Please enjoy these elusive grandidierite gemstones while you can, because we do not anticipate another lucky find such as this in the foreseeable future.

New Arrivals Back to Top

Our new arrivals include a collection of rainbow moonstone cabochons in ovals and rounds ranging in size from 7 to 18 mm. Rainbow moonstone is actually a variety of labradorite (plagioclase feldspar) and true moonstone is potassium feldspar (AKA orthoclase). The highly-prized sheen, (adularescence) of rainbow moonstone led to it being called "moonstone".

Rainbow Moonstone Cabochon
Rainbow Moonstone Cabochon

Something that we have not seen for a long time is star sunstone, an aventurescent feldspar gemstone with asterism (the star effect). Sunstone is prized for its glittery aventurescence and star sunstone has this in addition to a four-rayed star. We currently have a nice selection of these sparkling star sunstone cabochons from India.

8-Carat Star Sunstone Cabochon
8-Carat Star Sunstone Cabochon

Kunzite is a pink to violet spodumene gem named after American mineralogist, George Frederick Kunz that we usually have in stock. We have recently bought some stunning kunzite specimens, along with some unusual kunzite cabochons. Kunzite stones not only possess unique and fabulous color, but can also be found in large sizes, making them perfect for pendants and cocktail rings.

Violet Kunzite Gemstone
Violet Kunzite Gemstone
Gem & Jewelry News for November 2017 Back to Top

The largest gem-quality black star sapphire discovered by James Kazanjian in Queensland, Australia has been fashioned into a necklace by Robert Procop and named the "Star of Jolie", after actress, Angelina Jolie. The rough sapphire weighing 1,113 carats, which was cut into an 888.88-carat pear-shaped cabochon, mounted in rose gold and surrounded by smaller black star sapphire cabochons, is up for sale for $5 million. The proceeds of the sale will go to the Education Partnership for Children of Conflict (EPCC), founded by Angelina Jolie. For those who are curious to see the enormous black star sapphire necklace, it can be viewed at Saks Fifth Avenue in Palm Desert, California and Bal Harbour, Florida, before it is exhibited at the Smithsonian in Washington D.C. The second-largest gem-quality black star sapphire in the world is the Black Star of Queensland, which weighs 733 carats. The world's largest blue star sapphire is the "Star of Adam", which weighs 1,404.49 carats and was discovered in Ratnapura, Sri Lanka.

The Donnersmarck Diamonds; a pair of fancy intense yellow diamonds previously owned by famous 19th-century French courtesan, La Païva, Countess Henckel von Donnersmarck will be offered for auction at Sotheby's on 15th November. The Diamonds consist of a 102.54-carat cushion-cut stone and a pear-shaped 82.47-carat stone, and are expected to reach between 9 and 14 million USD. La Païva rose from modest Russian roots to the pinnacle of Parisian aristocracy; upon her second marriage, to Count Guido Henckel von Donnersmarck, she became the owner of some fabulous jewels, including the Donnersmarck Diamonds. The Diamonds remained in the Donnersmarck family collection until 2007 when they were purchased separately for $4.7 and $3.3 million.

An Institute for Pearls and Gemstones has been established in Bahrain, as part of a national plan to revive the pearl industry in the Kingdom. Pearls from the Persian Gulf were an important source of income for the region for centuries, but went into decline after the 1930s.

Customer Questions Back to Top

Every month we answer questions of general interest from our customers. Please feel free to send your questions or suggestions to our support team at!

Hi, I'm looking for a nice, decent-sized faceted green gem pair to make a pair of earrings with, what do you suggest?
Depending on the exact green you're looking for, there are several choices. The largest faceted green gems we offer are elongated green tourmaline baguettes, which range from medium-green to blue-green in lengths measuring up to 30 mm, making them perfect for long pendant earrings. These are sold as single gems, but we would be happy to find a matching pair for you. Probably the most affordable green faceted gemstone in large sizes is green agate, which is a beautiful, medium to bottle green color. If you prefer a more pastel green, prehnite would be ideal. Chrome diopside is a beautiful forest-green stone with a higher level of transparency than agate and prehnite. As for bright green, peridot is a great choice with a bright yellowish-green color, even in low lighting, which is why it was nicknamed, "evening emerald". For higher budgets, smaller matched pairs of emerald, tsavorite garnet and green sapphire are great choices for timeless earrings. To learn more about green gemstones and make an informed choice, please see our comprehensive green gemstones article.
Dear GemSelect, can you advise me on how to tell natural, mined ruby and sapphire from synthetic, lab-created gemstones?
Since lab-created corundum (ruby and sapphire) is chemically and physically equivalent to naturally-mined corundum, it can be tricky to determine. However, with strong magnification, it is possible to see a difference in growth lines. While natural rubies and sapphires have parallel growth lines, lab-created stones have curved growth lines. Another feature of natural corundum stones is that they contain solid inclusions, while lab-created stones do not. An experienced gemologist should be able to help take a look, but a general rule is that if the price is lower than normal and the stone is unusually clean, then it could be synthetic or a simulant.

We always welcome your questions, comments and feedback! For those who are interested in attending some gem and jewelry events, please see the details below.

Gem & Jewelry Events for November 2017 Back to Top
Event Name
Event Name
Mid-South Jewelry & Accessories Fair
Memphis Cook Convention Center, 255 N Main Street, Memphis, TN 38103, USA
November 2 - 5, 2017
Event Name
Taiwan Jewellery & Gem Fair
Taipei World Trade Center (TWTC) Hall 1, No. 5, Section 5, Xinyi District, Taipei City, Taiwan 110.
November 3 - 6, 2017
Event Name
Fall Bead & Jewellery Fair
Central YMCA, 2nd Floor, 20 Grosvenor Street, Toronto, ON, Canada
November 4, 2017
Event Name
Cheltenham Rock, Gem 'n' Bead November Show
Cheltenham Racecourse, Evesham Rd, Cheltenham, GL50 4SH, UK
November 4 - 5, 2017
Event Name
Beijing Mineral and Fossil Show
Building 5, China International Exhibition Center (CIEC), 6 East Road of North 3rd Ring, Beijing City CBD, Beijing, China
November 9 - 13, 2017
Event Name
International Gem & Jewelry Show Denver
Denver Mart (Pavilion Building) 451 E 58th Ave, Denver, CO 80216, USA
November 10 - 12, 2017
Event Name
Melbourne Bead Expo
Holmesglen Institute, Conference Centre, Corner Warrigal & Batesford Roads, Chadstone, Melbourne, Australia
November 10 - 12, 2017
Event Name
Hall 4, Gate 5 Teodorico at Fieramilanocity, Milan
November 10 - 13, 2017
Event Name
VOD Dubai International Jewellery Show
Dubai World Trade Centre, Sheikh Zayed Rd, Dubai, UAE
November 15 - 18, 2017
Event Name
Jewellery Arabia 2017
Bahrain International Exhibition and Convention Centre (BIECC), Building 158, Avenue 28, Sanabis, Block 410, P.O. Box 11644, Kingdom of Bahrain
November 21 - 25, 2017
Event Name
GLG Jewelry & Fine Agates
Landmark Center, 75 5th Street E, Saint Paul, MN 55102, USA
November 30, 2017

Keep up with our new arrivals before they hit the newsletter by joining our thousands of fans and followers on our social networking pages. We love interacting with our customers - you can visit us on Tumblr, LinkedIn, Twitter, Facebook or Pinterest!

To ensure you can receive our emails, please be sure to add to your list of safe contacts, or you add us into your email address book! Please feel free to contact us with any questions, comments and queries! We respond to each and every email we receive.

Happy Gem Hunting!
Your friends at GemSelect

  • 初刊: 10月-31-2017
  • 最終アップデート: 11月-01-2017

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Gems are always measured in Millimeter (mm)

Dimensions are given as;
length x width x depth,
except for round stones which are;
diameter x depth

Select gems by size, not by weight!
Gem varieties vary in density, so carat weight is not a good indication of size

Note: 1ct = 0.2g

Size Comparison Chart