GB/T 34543-2017Yellow diamond grading (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009. This standard proposed by the Ministry of Land and Resources. This standard by the National Gems Standardization Technical Committee (SAC/TC298) centralized. This standard was drafted unit. Ministry of Land and Resources jewelery jewelery management center Beijing Institute of jewelry, jewelery quality supervision and inspection center. The main drafters of this standard. Zhang Jian, Lu Taijin, Xu Yingqian, Liu Houxiang, Chen Hua, Song Zhonghua, Lan Yan, Ke Jie, Bi Lijun. Yellow diamond grading

1 Scope

China's national standard for grading yellow diamonds. It specifies the grading rules for natural, untreated, unmounted polished yellow diamonds, and mounted stones may be graded with reference to it. Colourless diamond is graded on the absence of colour, and the whole familiar scale from D downwards measures how much yellow tint a stone has - with more tint meaning less value. Yellow diamond inverts that completely. Past a certain saturation the stone stops being a poor white and becomes a fancy colour, and the scale reverses: more colour is worth more, and the finest are worth multiples of a colourless stone of the same weight. The awkward part is the transition. There is a range where a stone is neither a good white nor a good yellow, and where it falls decides its price by a wide margin. That is what a grading standard for yellow diamond has to pin down, along with the hue - a yellow leaning brown or green grades differently from a pure one - and the conditions of observation.

This standard specifies the natural un-polished non-polished yellow diamond grading rules. This standard applies to non-mosaic polished yellow diamond grading, mosaic polished yellow diamond grading can refer to the implementation of this standard.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version applies to this article Pieces. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 16552 name of jewelry jade

GB/T 16553 jewelery identification

GB/T 16554 diamond grading

3 Terms and definitions

GB/T 16552, GB/T 16553 and defined by the following terms and definitions apply to this document.

3.1 Diamond An equiaxed crystal natural mineral consisting of carbon atoms with a Mohs hardness of 10, a density of 3.52 (± 0.01) g/cm3, a refractive index of 2.417, a dispersion value 0.044.

3.1.1 Yellow diamond yelowdiamond The main color tone is yellow, chroma to light color diamonds.

3.2 Yellow diamond graded yelowdiamondgrading From the color, clarity, quality and other aspects of the yellow diamond grade, and cut its evaluation.

3.3 Color grading colorgrading Using colorimetry, the color of the yellow diamond is graded under specified conditions.

3.3.1 Hue hue Diamond yellow, green, orange and other colors of the characteristics.

3.3.2 Saturation chroma Yellow diamond color intensity level.

3.3.3 Brightness value Yellow diamond color brightness level.