Opal can range from 5 to 6.5 on the Mohs hardness scale. Hardness and toughness Gem and mineral hardness is measured on the Mohs scale. The numbers are based on the relative ease or difficulty with ...

For centuries, the Mogok Stone Tract of Burma has provided the world with its finest rubies. The mining district is situated about 700 km north of the capital city of Rangoon, with the rubies found ...

Below is the list of recognized holidays when GIA locations will be closed.View the holiday schedule for all GIA locations worldwide.

This chart focuses primarily on the types of natural inclusions found in tourmaline, as well as the minerals in which tourmaline can be found as an inclusion. Treatments such as enhancement of ...

Figure 1. Diamonds such as this 1.15 ct round brilliant are some of the most highly sought-after gem materials and may contain inclusions that give the gemologist clues about their origin or treatment ...

Figure 1. These 20 completely non-nacreous pen pearls, from the group of 22 samples in this study, are set against a pen shell displaying both nacreous (left) and non-nacreous areas (right). Photo by ...

Figure 1. The vivid colors seen in fine gem-quality spinel are derived from the mixing between multiple different chromophores in a range of ratios and concentrations, as in this fine 13.52 ct ...

An Identification Report, with geographic origin added. For polished, loose or mounted natural alexandrite, emerald, jade, Paraíba tourmaline, red spinel, ruby, and ...

The traditional gemological technique for distinguishing natural from synthetic blue spinel has involved the use of refractive index and absorption spectra. Recently, however, the standard ...

330 克拉的亚洲之星收藏在国家自然历史博物馆中 -Chip Clark,Smithsonian Institution 友情提供 传统上，蓝宝石象征着高贵、真理、真诚和忠诚。 长达几个世纪的时间里，蓝宝石用于装饰皇室及神职人员 ...

Practice the same time-tested procedures and identification skills used by the Institute’s renowned gemological experts. Tools used include a microscope, a refractometer with polarizing filter and a ...

The soothing soft pink shades of rose quartz appeal to gem carvers and collectors. – Valerie Power, courtesy Arunashi People accept a certain amount of sand, dirt, and dust as ordinary ingredients in ...