Product testing method Grading method of lab grown Ruby

Ruby grading is mainly divided into quality grades from the aspects of color, clarity, fire color and quality.

1、 Color grading

The color of ruby is classified by colorimetry under the specified environment.

Observation method:

under the specified observation environment, make the gem about 25cm away from the light source, hold the gem waist, observe the gem from the table direction, shake the gem about 30°angle, and classify the color of the gem according to the reflection color and fire color.

Description method:

the ruby color is described in the way of chromaticity + hue, for example, the hue is purplish red, the chromaticity is crimson, and its color is described as dark purplish red. If the chromaticity level is red, the color is directly described as red, purple or orange.

2、 Larity grading

Observation method:

under specified conditions, observe the type, size, number and location of internal and external characteristics of gemstones, and divide the cleanliness level according to its impact on the beauty of gemstones.

3、Briliance grading

Observation method:

under the specified observation environment, make the gem about 25cm away from the light source, hold the gem waist, observe the gem crown from the table direction, shake the gem about 30°angle, and divide the fire color level according to the proportion of brilliance in the crown area and brightness.

4、 Heat treatment

Observation method:

under the specified conditions, observe whether the inclusions (acicular rutile fracture, zircon halo, etc.) in the gem have changed to distinguish whether they have undergone heat treatment; Then, on the premise of determining the heat treatment of gemstones, the heat treatment categories are further divided according to the amount of residues in cracks and / or pits.

5、 Grading requirements

Environmental requirements: 

Ruby grading shall be carried out indoors without direct sunlight, and the color tone of grading environment shall be white or neutral gray. During grading, the specified graded light source shall be used for lighting, and the neutral white (light gray) paper (board) without fluorescence and obvious directional reflection shall be used as the observation background.

Gradinglight:

The color temperature of the lighting source used for Ruby grading is 4500k ~ 5500k, and the color rendering index is not less than 90.