In November 2022, a parcel of 24 approximately 0.5–1.2 ct spinel crystals, described as cobalt-diffused, were obtained directly from a treater by the research team at GIA in Bangkok. Of these, seven ...

Le Ngoc Nang, Pham Minh Tien, Pham Minh, and Pham Trung Hieu Anorthoclase, (Na,K)AlSi 3 O 8, is an uncommon variety of alkali feldspar that is the potassium-rich variety of high albite, distinguished ...

GIAについて 1931年設立の独立非営利組織であるGIA（Gemological Institute of America）は、宝石学における世界有数の権威として認められています。GIAはカラー、クラリティ、カット、カラット ウェイトからなる有名な4Cを考案し、さらに1953年にはダイヤモンドの品質の基準として世界中で認知されて ...

Figure 1. Lath-like mineral inclusions of grandidierite were seen in this sapphire at GIA’s Carlsbad laboratory. Photomicrograph by Nathan Renfro; field of view 2.61 mm. Recently the authors ...

Laboratory-grown CVD rough diamond (left), laboratory-grown HPHT rough diamond (middle) and natural rough diamond (right) Two specimens of faceted crystalized carbon - both are crystal clear and give ...

How Do Lithospheric Diamonds Form? Lithospheric diamonds (box B) often contain detectable nitrogen, implying that they crystallize from carbon- and nitrogen-bearing (C-N-bearing) fluids. Through the ...

GIA has studied lab-grown or manmade diamonds extensively over the past 30 years, and we know a great deal about the methods used to produce them and how they can be recognized. While synthetic ...

Figure 1. A comparison of the Mohs hardness scale and the Knoop hardness scale, a micro-hardness test where a pyramidal diamond point is pressed into the polished surface of the sample with a known ...

宝石爱好者通常将其形容为“白天的祖母绿，晚上的红宝石”，亚历山大变石是金绿玉矿物中非常罕见的变色类别。 它最初在 19 世纪 30 年代被发现于俄罗斯的乌拉尔山脉，现在，斯里兰 卡、东非和巴西都发现了它的身影，尽管如此优良的材料依然非常稀少而珍贵。 亚历山大变石描述 亚历山大变石 ...

实际上，拓帕石拥有非常广泛的颜色范围，除褐色外，还包括各种色调和色度的蓝色、绿色、黄色、橙色、红色、粉红色和紫色。 无色拓帕石色彩度饱满，通常经处理后使其呈蓝色。 拓帕石也具有多向色性，这意味着，这种宝石能在不同的晶体方向呈现不同的色彩。 拓帕石描述 拓帕石的历史与 ...

Diamond Origin Report Full 4Cs assessment with a plotted clarity diagram, geographic origin and GIA report number laser inscription. For loose, natural D-to-Z color diamonds only, weighing 0.15 carats ...

The 3309 cm –1 Series in Sapphire and Ruby: A Focus on FTIR Peak Position Variation Investigates the correlations between peak positions in the 3309 cm –1 series with trace element concentrations for ...