GIA

GIA

giagrams

A fantastically rare gem, the Winston Red diamond now takes center stage in a newly opened exhibit of fancy colored diamonds at the @SmithsonianNMNH. Weighing 2.33 carats, it's the fifth-largest confirmed Fancy Red diamond ever documented, remarkable for its pure, unmodified red hue. ♦️✨ Dive deeper into the Winston Red’s captivating story in the latest Gems & Gemology cover article from GIA, exploring its extraordinary properties, historical significance and likely geographic origin at the link in our bio. Photos of the Winston Red by Robert Weldon; courtesy of Ronald Winston, sketch courtesy of Archives Cartier London © Cartier

07.18 02:07

GIA 的更多帖子

Spinel comes in a variety of rainbow hues and are found all over the world! Here is a look at some notable origins. 🌈 🇲🇲 Myanmar (formerly Burma): Famous for rich, ruby-like red spinels and hot pink spinels with exceptional clarity. Many are found in the legendary Mogok Tract and Namya. 🇹🇯 Tajikistan: Known for pink to red spinel, especially from the historic Kuh-i-Lal mines. The colors here can have less saturation thanks to high chromium content. 🇱🇰 Sri Lanka: Produces a wide range of colors, including blue, cobalt blue and violet spinels. 🇻🇳 Vietnam: Yên Bái and Luc Yen spinels are prized for their red, blue and pink spinels. 🇹🇿 Tanzania: Mahenge spinels dazzle with electric pink to reddish hues and are bright and eye-catching. Blue spinels are also found here. Spinel is a truly globe-trotting gem! Which is your favorite spinel color? 🌍💫 Learn more about spinel origins on our website at the link in our bio.
Peridot and spinel, August's birthstones, come with stories as colorful as the gems themselves! 💚💙 Peridot, the gem variety of the mineral olivine, forms deep within the Earth and is brought to the surface by geologic processes, including volcanoes. Some have also hitched a ride to Earth inside billion-year-old meteorites. “The great imposter,” spinel, comes in a rainbow of colors and has spent centuries hiding in plain sight. Red spinel was often mistaken for ruby. In fact, the famous Black Prince’s Ruby in the British Imperial State Crown is actually a 170-carat red spinel! Another prized variety is cobalt spinel, a rare gem beloved for its electric blue glow. Learn more about August’s birthstones on our website at the link in our bio.
For many gemologists and jewelry enthusiasts, a ruby’s origin adds to its allure. GIA determines country of origin using two primary methods: trace element analysis and inclusion analysis. Rubies from different regions exhibit distinct chemical signatures. Inclusions also vary by origin. For instance, Madagascar rubies are known for showing an abundance of zircon inclusions (image 2). Together, these chemical and visual clues reveal the geological conditions of a ruby’s formation, allowing gemologists to accurately determine its geographic origin. What makes GIA a leader in ruby origin determination? - Our World-Class Gemstone Database: GIA’s expert field gemology team has conducted over 100 expeditions and collected more than 29,000 reference samples. - Advanced Instrumentation: Tools like LA-ICP-MS and microscopy enable precise, accurate analysis. - Expert Researchers: GIA employs the highest number of PhDs in the industry, driving innovation and accuracy in origin determination. Learn about ruby origin determination in the groundbreaking article of G&G at the link in our bio. Rough specimen: Gift of William F. Larson, @palainternational. Right oval cut stone: Courtesy of Edward Boehm Photomicrograph details in images 2 and 3 in comments.
All cut from one extraordinary 108.39-carat pink diamond crystal, the Kao Legend Collection showcases seven breathtaking pink diamonds seen here in its GIA Monograph. The centerpiece of the collection is the 20.49-carat Kao Legend diamond, graded Fancy Intense Purplish Pink by GIA. The accompanying satellite diamonds span a spectrum from Fancy Intense Purplish Pink to Faint Pink. 🩷 Each diamond is a gemological marvel in its own right, but together they form a truly rare, exceptional suite. Adding to their allure, all are type IIa diamonds—the most chemically pure type of diamond, comprising less than 2% of all natural diamonds. The remarkable crystal that produced these gems was discovered in the Kao Mine in Lesotho. The Kao Mine is one of Lesotho’s largest diamond mines and has produced several notable pink diamonds, including the famed 47.80-carat Pink Eternity. Learn more about Fancy Pink diamonds on our website at the link in our bio. Stone collection courtesy @chorongroup
Rubies have been mined for over 2,000 years—yet new deposits continue to be discovered today. ⛏️ Ruby deposits from historic to modern include: - 🇲🇲 Myanmar (formerly Burma): A historic source, the Mogok stone tract has been mined for fine rubies for likely 2,000 years. Myanmar is known for producing highly valued “pigeon’s blood” rubies with strong fluorescence. - 🇹🇭 Thailand: An important historic producer, Thai rubies typically have darker tones and weaker fluorescence due to higher iron content. Production has declined in recent years, but Thailand remains an important cutting and trading center. - 🇱🇰 Sri Lanka: While most well-known for its sapphires, Sri Lanka also produces rubies that typically have lower saturation and clarity. Star rubies are also found here! - 🇲🇿 Mozambique: The discovery of rubies in Montepuez in the early 2000s transformed the world’s ruby market. Since then, Mozambique has become the most important producer of fine rubies in recent years. Other notable sources of rubies include Vietnam, Madagascar, Tanzania, Greenland, Afghanistan, Tajikistan and more. Learn more about different ruby origins on our website at the link in our bio. Image 1 courtesy of Edward Boehm/RareSource. Photo: Robert Weldon
Meet the largest Fancy Vivid Yellow-Orange diamond ever examined by GIA (as of 2025)! In every way, this gem is an exceptional natural wonder 💎🧡 According to its Monograph issued by GIA, this remarkable 13.50-carat cushion cut took four months to craft from a 34.21-carat crystal, which also produced two satellite stones weighing 4.14 carats and 1.04 carats. Additionally, predominantly orange diamonds are exceptionally rare, making up less than 2% of all fancy color diamonds submitted to GIA each year. Orange diamonds over one carat in size are even more rare. Finally, this diamond’s saturated hue is caused by single nitrogen atoms dispersed throughout the crystal lattice, making it a rare type Ib diamond. Learn more about fancy color diamonds on our website at the link in our bio.
While Montana is renowned for its sapphires, a rare few rubies have been unearthed in the Rock Creek region. In the Summer 2019 edition of G&G, only 29 rubies—totaling just over six grams (or 30 carats)—had been recovered from more than 400 kilograms of mined material! It’s even possible that many of these rubies have been discarded over the years as miners may have mistaken them for garnets. Montana rubies are distinguished by their inclusions, such as glassy melt features with reflective hexagonal films and loosely spaced rutile needles (image 2), traits typical of Montana sapphires in general. Have you ever seen a Montana ruby? Read more in the 2019 G&G article at the link in our bio. Image 1: Courtesy Jeffrey R. Hapeman, Earth’s Treasury Photomicrographs in image 2 courtesy of Claire Malaquias
The Tiffany Yellow, the Dancing Sun and the Sun-Drop Diamond have made yellow diamonds a symbol of warmth, prestige and rarity. With hues ranging from soft lemon to deep golden canary, these stones have dazzled collectors and dominated the spotlight at major auctions. Though more common than blue diamonds, the finest yellow diamonds—especially large, naturally saturated ones—remain exceptionally rare. Here are a few countries where notable specimens have been found: - 🇨🇦 Canada: The Dancing Sun (204.36 carats, Fancy Intense Yellow) was cut from the largest known gem-quality diamond rough ever mined in North America (552.74 carats). - 🇨🇩 Democratic Republic of Congo: The 303.10-carat Fancy Deep Brownish-Yellow Golden Canary was cut from the famous Incomparable Diamond. The original 890-carat rough was found in the 1980s by a little girl playing in her uncle’s backyard! - 🇿🇦 South Africa: Known for the Oppenheimer Diamond (253.7 carats, uncut) and the Sun-Drop Diamond (110.03 carats, Fancy Vivid Yellow), both museum-worthy in size and hue. - 🇷🇺 Russia: The Fancy Vivid Yellow Firebird (20.69 carats) and recently unveiled New Sun (100+ carats) diamond showcase the rich yellow colors that can be found in Siberia. Which of these golden gems is your favorite? Learn more about GIA’s Fancy Color Diamond grading at the link in our bio.
In this necklace, all the Burmese rubies—and even some of the diamonds—fluoresce beautifully under UV light! 🌟 Chromium is the trace element that not only gives rubies their signature red hue but also causes red fluorescence, intensifying the gem’s color with a coal-like glow in natural sunlight. Rubies formed in marble, like those from Myanmar (formerly Burma), Vietnam and Afghanistan, often exhibit strong fluorescence due to low iron content, since iron can suppress fluorescence. In contrast, high-iron rubies such as those from Thailand, Mozambique and Madagascar, typically show weaker fluorescence because of their higher iron content. Learn more about what gemstone fluorescence can tell us about gems at the link in our bio.
『关注公众号 instome 解锁更多功能』

微信扫描二维码登录