GIA’s Fall Gems & Gemology is now available for free online. In this season’s issue, very rare and fascinating diamond properties bring out the nerd in the desk gemologist.
First up, the main feature story examines the broad 480 nm absorption band, which accounts for saturated yellow body color, pure orange body color (orange with no modifiers, such as yellowish-orange, or brownish-orange), and very rare “chameleon” diamonds, diamonds that change color when exposed to sunlight or heat. Diamonds that exhibit this 480 nm broad band are very rare diamonds which, so far, are only known to be mined in Russia and Canada.
Then there’s the feature that examines the unusual formation of diamond contact twins, otherwise known as “macles.” These thick triangular rough crystals have always fascinated gemologists for their unusual shape as well as wonderful surface markings. This feature goes even further to study not only the outer appearance, but also in how these crystals grow – examining the interior structure of macles.
G&G covers a huge variety of topics, including the three feature articles, Lab Notes, G&G Micro-World, Gem News International, and the return of the Diamond Reflections column, titled “Raw Brilliance: Nature’s Diamond Sculptures,” examining some very interesting rough diamond shapes.
This and every issue of G&G since 1934 are available at no cost on GIA’s website at GIA.edu/gems-gemology. Images are available upon request if you are interested in featuring or highlighting any of these exciting articles.
Take a moment and check out the feature articles:
A Guide to Diamonds with the 480 nm Absorption Band
Mei Yan Lai
Summarizes the features of 480 nm band diamonds, including chameleon diamonds and those with unmodified orange hues, for rapid identification or advanced gemological testing.
Ahmadjan Abduriyim and Masao Kitamura
Investigates the morphological changes of macle diamonds during the growth process by exploring their three-dimensional internal zonal structure.
Meiyu Shih, Guangahi Shi, and Biqian Xing
Examines correlations between surface microstructures and the orange peel effect in Russian white nephrite, proposing a formation model and revealing distinctive microfeatures specific to the material.
G&G’s regular features include:
- Lab Notes provides reports from GIA’s global laboratories, including details about a remarkable bicolor natural rough diamond.
- G&G Micro-World highlights a “UFO” in diamond, a natural opal with unusual play-of-color resembling a turtle shell, a suspended pargasite crystal in pink spinel, and more.
- Diamond Reflections showcases the diverse natural shapes of rough diamonds and explores how geological processes create their unique forms.
- Gem News International features several interesting topics, including two types of stones from Myanmar—amber displaying Palaeoclavaria burmitis inclusions and a large eight-rayed star peridot.
Join the conversations on GIA’s Gems & Gemology Facebook group with an online community of more than 45,000
