Article Search Results

Types

Articles (78)

Content Type

Lab Notes (3) Gem News International (6) Reviews (1) Abstract (3) Feature (9) Micro-World (1)

Reviewed

Peer Reviewed (38)

Topics

See All Topics

Gemstones

Diamond (21) Emerald (14) Ruby (12) Sapphire (12) Pearl (3) See All Gemstones

XClear Selections

Rare Double-trapiche Emerald

Tao Hsu, March 29, 2013

At the AGTA show, Equatorian Imports showed this contributor two pieces of emerald with a very rare double-trapiche pattern

Zoned Scapolite from India

Gagan Choudhary , March 29, 2013

This contributor encountered parcels of rough and faceted scapolite that appeared strongly zoned to the unaided eye.

DiamondView Imaging of the Pavilion Facets

Pseudo-Synthetic Growth Structure Observed in Natural Diamond

Paul Johnson, March 29, 2013

This stone was a good example of a very rare natural diamond exhibiting synthetic growth characteristics.

Iridescence in iris quartz from Jalgaon, India

Causes of Iridescence in Natural Quartz

Xiayang Lin and Peter J. Heaney, May 8, 2017

Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.

Article

Spring 2023 G&G Available Now

Erica Zaidman, May 23, 2023

An overview of the Spring 2023 Gems & Gemology content.

Figure 1. A 4.56 ct rough diamond with plastic deformation lines, highlighted in the sketch on the right. Deformation has occurred along a set of parallel internal slip planes. The planes appear as thin ridges on the diamond’s surface, exposed by natural dissolution of the surface by fluids (i.e., resorption). In fact, the whole surface has been resorbed into this overall dodecahedroid shape, decorated by elongate hillocks and plastic deformation lines, both fine features representing slight interruptions and imperfections in the diamond crystal lattice. Images by Evan M. Smith.

Plastic Deformation: How and Why Are Most Diamonds Slightly Distorted?

Evan M. Smith, May 23, 2023

A look at plastic deformation, one of the most prevalent features in natural diamond.

Figure 1. Left: This 1.63 ct grayish blue diamond was identified as a CVD synthetic, with its color caused by both the GR1 and SiV<sup>–</sup> centers. Photo by Xiaoyu Zhang. Right: Dark cloud-like non-diamond carbon inclusions. Photomicrograph by Meng Li; field of view 0.25 mm.

Grayish Blue CVD Diamond Colored by GR1 and SiV^–

Wang Yang, Xiaoyu Zhang, and Zhonghua Song, May 23, 2023

Examination of a grayish blue CVD laboratory-grown diamond indicates its color was caused by both the GR1 and SiV^– centers.

Figure 1. These examples of gem minerals that formed in magmatic environments are part of GIA’s Eduard Gübelin Collection. From top to bottom and left to right: 29.96 ct sanidine feldspar from Germany, 53.00 ct peridot from Myanmar, 11.58 ct zircon from Thailand, 20.66 ct topaz from Utah, 2.05 ct sapphire from Thailand, 18.36 ct pyrope garnet from the Czech Republic, 19.55 ct black spinel from Thailand, and 2.50 ct ruby from Thailand. Photos by Robert Weldon.

Gems Formed in Magmatic Rocks

Aaron C. Palke and James E. Shigley, January 25, 2023

This installment of “Colored Stones Unearthed” covers gemstones that formed in magmatic environments and the insights they offer into the evolution of the earth and the geological processes that shaped our world.

A 20 ct faceted spinel from the Kul-i-Lal deposit of Tajikistan.

Color Mechanism and Spectroscopic Thermal Variation of Pink Spinel Reportedly from Kuh-i-Lal, Tajikistan

Yicen Liu, Lijian Qi, Dietmar Schwarz, and Zhengyu Zhou, November 11, 2022

A detailed spectroscopic investigation of the color of pink spinel reportedly from the Kuh-i-Lal deposit in the Pamir Mountains of Tajikistan.

Muling sapphires showcasing the wide range of color and clarity from this deposit.

Sapphire Beneath the Rich Black Soil of Muling, Northeastern China

Yimiao Liu and Ren Lu, November 11, 2022

A comprehensive look at the gemological features and advanced analysis of blue and fancy-color sapphire from the agricultural area of Muling, China.

Article Search Results

Types

Content Type

Reviewed

Topics

Topics

Gemstones

Gemstones

Find a Retailer

Shop the Campus Store

Subscribe to Knowledge Rocks Emails

Learn About Diamond Origin Reports