Article Search Results

Types

Articles (329)

Content Type

Lab Notes (44) Gem News International (32) Abstract (4) Feature (23) Micro-World (2)

Reviewed

Peer Reviewed (188)

Topics

Color (329)

Gemstones

Diamond (48) Sapphire (43) Pearl (26) Ruby (21) Emerald (12) See All Gemstones

XClear Selections

This 0.69 ct alexandrite showed a stellate structure due to cyclic crystal twinning and pleochroism, producing a kaleidoscope effect when rotated. These photomicrographs were taken with a single polarizer placed above the stone and a white diffuser below the stone to highlight the color. Photomicrographs by Makoto Miura; field of view 9.80 mm.

“Kaleidoscope” in Alexandrite

Makoto Miura, January 26, 2024

Pleochroic colors caused by cyclic twinning produce a kaleidoscope effect in alexandrite.

Rough diamond crystals exhibiting both pink and colorless sections.

Bicolor Rough Diamond Crystals

Sally Eaton-Magaña, Paul Johnson, Ellen Barrie, and Michaela Hariňová, July 9, 2021

Two Australian rough diamonds demonstrate both pink and colorless sections in the same crystal.

Figure 1. This 0.63 ct tapered baguette-cut diamond showed two major color zones. Photo by Adriana Robinson.

Rare Natural Bicolor Diamond

Mei Yan Lai and Sally Eaton-Magaña, January 26, 2024

A tapered baguette-cut diamond exhibits two major color zones.

A 16.71 ct transparent orange-yellow oval sodalite measuring 17.61 × 15.74 × 12.88 mm. Photo by Lhapsin Nillapat.

A Remarkable 16.71 ct Transparent Orange-Yellow Sodalite

Narint Jaisanit, January 26, 2024

A rare and exceptional example of sodalite is studied in the Bangkok laboratory.

Figure 1. The “Infinite Blue,” an 11.28 ct Fancy Vivid blue diamond, sold for $25.3 million in Hong Kong. Courtesy of Sotheby’s.

Fall 2023 Auction Highlights

Erica Zaidman, January 26, 2024

Large blue and pink diamonds were among the top lots of the fall auction season, including the most expensive auction jewel of 2023.

The newly discovered variety of amblygonite-montebrasite is unique for its blue color. It often has a mottled appearance with alternating blue and creamy white patches. The faceted stone weighs 0.83 ct. Photo by Lhapsin Nillapat.

Blue Amblygonite-Montebrasite from Rwanda

Wim Vertriest, Gil Yuda, and Joe Henley, January 26, 2024

A report on a new blue variety of amblygonite-montebrasite from Rwanda.

Article

Fall 2023 G&G Available Now

Erica Zaidman, November 3, 2023

An overview of the Fall 2023 Gems & Gemology content.

Fire Obsidian’s Beguiling Spectrum

Robert Weldon and Nathan Renfro, August 4, 2023

A look at a rare volcanic glass from central Oregon with lapidary artist Tom Dodge.

Figure 1. These exceptional natural yellow sapphires from Madagascar (2.1–2.6 ct) represent both the Fe<sup>3+</sup> chromophore and the trapped hole paired with Fe<sup>3+</sup>. Photo by Ronnakorn Manorotkul/Lotus Gemology; courtesy of GemFever.

Yellow Sapphire: Natural, Heat-Treated, Beryllium-Diffused, and Synthetic

John L. Emmett, Ungkhana Atikarnsakul, Jennifer Stone-Sundberg, and Supharart Sangsawong, November 3, 2023

Investigates the various chromophores responsible for color in four types of yellow sapphire.

Figure 1. A good-quality 88.25 ct “chameleon” amber with a red bodycolor displaying a vivid green fluorescence color that appears to float on the surface. Photo by Yan Li.

The Special Color Effect in “Chameleon” Amber

Jinfeng Yang, Yan Li, and Youzhi Liang, November 3, 2023

An examination of three Burmese chameleon amber specimens using 3D fluorescence spectroscopy.

Article Search Results

Types

Content Type

Reviewed

Topics

Gemstones

Gemstones

Find a Retailer

Shop the Campus Store

Subscribe to Knowledge Rocks Emails

Learn About Diamond Origin Reports