The lack of a grading system for the popular stone has prompted a father-son team to spend the last five years working on one. Turquoise stones from the blue and green master sets at the Turquoise ...

Turquoise is one of the rare gems in the world. It is aquamarine and was a tribute to the royal families in the Qing Dynasty. Beijing Palace Museum alone collects about 10,000 turquoises. In foreign ...