Figure 1. Yellow, brownish gray, and near-colorless anorthoclase feldspar from southeast Vietnam. The rough stones range from 96.5 to 144.8 ct and the cut samples from 3.64 to 11.07 ct. Photos by Le ...

ONLINE EDUCATION PAYMENT PLANS Tuition payment plans are available for the online courses listed below with the first installment and a non-refundable $35 plan administration fee due at the time of ...

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 ...

海蓝宝石生日石的保养与清洁 这种三月生日石的 莫氏硬度 为 7.5 — 8，坚硬耐磨，适合日常佩带。海蓝宝石的保养非常简单。使用温水、温和的肥皂和牙刷，擦洗容易集纳污垢的生日石背面。 超声波清洗机 和蒸汽清洗通常是安全的方法，只要宝石内不含断裂或液体内含物。

GIA in BangkokLocated in one of the most vibrant cities in Southeast Asia and one of the world’s largest trading centers for colored stones, GIA in Bangkok is vital to our laboratory and education ...

Feature Gems & Gemology, Summer 2020, Vol. 56, No. 2 Optical Whitening and Brightening of Pearls: A Fluorescence Spectroscopy Study Chunhui Zhou, Tsung-Han Tsai, Nicholas Sturman, Nanthaporn ...

The published literature offers only a few records of direct measurement of the natural radioactivity in nephrite. The present study used high-purity germanium (HPGe) low-background gamma-ray ...

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 ...

Diamond washing at Golconda, from “A Nutshell of Knowledge Concerning the Mine” by Isaac Taylor, Second Edition, Published by John Harris, London, (1830) Diamonds have been known and celebrated in ...

Feature Gems & Gemology, Summer 2021, Vol. 57, No. 2 Detection of Color Treatment and Optical Brightening in Chinese Freshwater “Edison” Pearls Chunhui Zhou, Joyce Wing Yan Ho, Sally Chan Shih, ...

Figure 1. A silver brooch containing a large Slovak opal (77 ct, 34.5 × 25 × 13 mm) and 48 diamonds. The opal was initially purchased for Louis XVIII’s personal collection. In 1824, it adorned the ...

Fine-color, large, and eye-clean (lacking visible inclusions) rubies like this 11.01carat (ct) stone from Myanmar (formerly known as Burma) are extremely rare and valuable. – Photo: Robert Weldon/GIA.