Rapaport’s Post

#Trigons These are small triangular crystalline structures that can appear on the surface of rough diamonds, Trigons are surface features that occur during the diamond's growth process deep within the Earth's mantle. They can appear on any shapes of rough diamonds and are a good indicator that the rough is a diamond. Most other gemstones or minerals will not exhibit such growth patterns. #diamonds #gemstones #photomicrography #gemology #gemologist

What is a feather inclusion? 🪶 Take a look at this photomicrograph of a tourmaline. At the centre, we can see a spindly group of small cracks and fractures within the stone – these are commonly known as ‘feathers’ because of their wispy whitish appearance. Feathers are common internal features, and they don’t necessarily affect the beauty of a gemstone. It all depends on the size and placement of these cracks. Start learning about popular gemstones, like tourmaline, and the many natural features that make these minerals so fascinating with GemIntro. Study online, remotely and in your own time to kickstart your gemmology journey: https://lnkd.in/ea4mrdvA #GemAofGB #gemmology #tourmaline #featherinclusions #inclusions #photomicrograph #studygemmology #GemIntro

Here's a look at what you will find in Volume Two of the 5th Edition of the Handbook of Gemmology. Subjects include gem identification, coloured gemstone grading (including coloured gemstones, opals, jadeite and pearls) and of course diamonds! https://lnkd.in/gni69Ux5

"Excited to share that I’ve completed a Online Polished Diamond Grading course! 💎 Gained valuable skills in evaluating diamonds with precision. Ready to shine brighter in the gemology world! ✨ #DiamondGrading #SkillDevelopment #Gemology"

As a gemmologist, we are encouraged to collect stones for reference. With a reference collection of over 200 stones (and increasing!), my understanding of gems is such that I have been able to get an understanding of gems which I wouldn't have gotten without collecting them. For example, via the distant vision method (aka the spot method), the RI of quartz; variety chalcedony is 1.538 approx.

What do you know about Paraiba tourmaline? Many people associate it with its distinctive neon blue color. According to the LMHC, A paraiba tourmaline is a blue (electric blue, neon blue, violet blue), bluish green to greenish blue, green or yellowish green tourmaline, of medium-light to high saturation and tone (relative to this variety of tourmaline), mainly due to the presence of copper (Cu) and manganese (Mn) of whatever geographical origin. The name of the tourmaline variety ‘paraiba’ is derived from the Brazilian locality Paraíba where this gemstone was first mined. - Tourmalines with only traces of copper and low colour saturation and / or outside of the defined colour range are not called Paraiba tourmaline6. - Iron-rich copper bearing tourmaline showing in the o-ray polarised spectrum (obtained by UV-Vis-NIR spectrometer) an absorption band at 700 nm higher than the 900 nm absorption band (related to Cu) is not called Paraiba tourmaline. SOURCE:LMHC Standardised Gemmological Report Wording (version 8; February 2023) PHOTO:GEM-QUALITY CUPRIAN-ELBAITE TOURMALINES FROM sAo JOSE DA BATALHA, PARAIBA, BRAZIL GEMS & GEMOLOGY Fall 1990

Carat or Metric Carat?? Carat is the international unit for the weight of gemstones, equivalent to 200 mg (0.2 gram), with the symbol “ct” which, as a symbol of a unit and not an not abbreviation, therefore it cannot be expressed as "cts" as if it was plural. The name comes from the Greek "keration", some say from the Arabic “qirat”, little horn, alluding to the shape of the carob tree pods (Ceratonia siliqua) which seeds served originally in the past as patronised weights. The unit was defined in the then-called Metric System (originally Système Métrique Décimal) in 1907 by the Comité International des Poids et Mesures in Paris and in the following years it was gradually incorporated as standard in national jurisdictions. In Gemmology text books the unit was then appropriately mentioned as “metric carat”. The Metric System, however, was discontinued in 1960 with the introduction of SI - Système Internacional d’Unités (International System of Units) with this unit then defined simply as "carat". Therefore, today, the unit is called carat, not metric carat. In the image, the Cullinan III and IV, with 94.40 ct and 63.60 ct, respectively, often called "Granny's Chips", as these were the favourites to queen Mary of England, depicted here wearing them as a brooch. The reported weight of the Cullinan diamond crystal found in 1905 from which these two gems were cut, varied considerably between 3,019 and 3,032 old carats, being today accepted the 3,106 ct. Photo Royal Collection Trust © His Majesty King Charles lll #diamond #jewelry #history #gemology

Do you want to see what is in Volume One of the 5th Edition of the Handbook of Gemmology? Click on the link below and see what all the excitement is about! https://lnkd.in/gbEkq3Cz

Not all eyes are cats eyes! 😼 🍯Chatoyancy, the fascinating optical effect where a band of light appears to glide across a gemstone's surface, is best known in the world of gemmology for its resemblance to a cat’s eye. This effect is most pronounced when a gemstone is cut as a cabochon, with a smooth, domed top and a flat bottom. The light reflects off parallel inclusions-often tiny, needle-like crystals or hollow tubes-creating that signature "eye". 🤝 While many gemstones, including tourmaline, apatite, and quartz, can display chatoyancy, only chrysoberyl (BeAl₂O₄) can be called a true "Cat’s Eye". In other chatoyant stones, such as quartz the effect is called "Tiger’s eye". 🫶 The magic behind chrysoberyl’s famous Cat’s Eye effect lies in the presence of the mineral rutile (TiO₂), composed primarily of titanium dioxide. These rutile parallel to each other inclusions interacts with chrysoberyl’s crystal structure, creating that sharp, luminous band of light. 🙌 A standout example is the 58.19-carats Maharani Cat’s Eye from Sri Lanka. With its impressive size, honey color, and sharp band of light, it exemplifies why chrysoberyl holds the title of the ultimate Cat’s Eye. This gem not only captures light-it captures the essence of what makes chrysoberyl truly unique among gemstones. 👐 In such large cabochons, appears ''milk and honey'' effect. When you hold the gemstone near a bright light, with the eye positioned at a 90º angle to the light, you'll notice a striking contrast: one side displays the rich '’honey'’ hue of the body color, while the other side appears ''milky" 🛑🛑🛑 Some information in this post is wrongly presented, see corrections by Jeffery Bergman, SGC SSEF, Accredited Senior Gemologist, AGA in comments 👇👇👇 📷 58.19-carats Maharani Cat’s Eye from Sri Lanka © Smithsonian Institution, Smithsonian Education, Smithsonian Enterprises #Chatoyancy #CatsEye #Gemmology #Gems #Gemstones #RareGems #Gemsinclusions #GemsEffects #OpticalEffects #Cabochons #Crystals #Minerals #Mineralogy #Chrysoberil #Maharani #Education

5 years ago in winter of 2019, GIA’s award-winning journal, Gems & Gemology (G&G), dedicated the entire issue to discussing country of origin for colored stones. This issue laid out how GIA scientists determine origin and the challenges and complexities of the process. With an in-house gemology team traveling the world to collect and research gem samples, GIA has the unique skills and experience to empower consumers with candid, knowledge-based determinations. Revisit this issue to learn about this pressing, multi-faceted topic on our website: https://bit.ly/3AOCWQ3