Quality grade of turquoise

Traditional gemological rating: turquoise is divided into three grades in terms of color, structure, purity, special pattern and speed reading. National standard rating: Based on the traditional gemological rating method, the rating method is further quantified, and a unified standard and operation specification are formulated for the quality rating of turquoise. Mainly from the color texture, surface cleanliness, transparency, luster, patterns and other aspects of turquoise rating.

colour

The color of turquoise is described from hue (H), saturation (S) and lightness (B) by using HSB color three-dimensional model. By colorimetry, the turquoise to be graded is compared with the standard color card, and the color card value closest to the green to be graded is the color grade of turquoise.

Quality of materials

According to its density, the texture of turquoise can be divided into three grades, namely, extremely dense (T 1), dense (T2) and ordinary (T3).

transparency

The transparency of turquoise can be divided into two categories: slightly transparent and opaque.

Bright, shiny; Shine, shine

The luster of turquoise can be divided into three categories: glassy luster, waxy luster and earthy luster.

Surface cleanliness

The surface cleanliness of turquoise is divided into three grades: extremely clean (C 1), dense (C2) and ordinary (C3).

figure

The patterns of turquoise mainly include Ulan flower, Tang tricolor, cobweb water grass pattern, water ripple pattern, raindrop pattern and so on.