Diamond quality evaluation
Diamond quality evaluation
The quality of diamonds is evaluated mainly from four aspects: carat weight, color, clarity and cut. Since the names of these four factors all start with “C”, they are referred to as 4C grading.
- Carat Weight
Carat is the unit of weight of diamonds. 1 carat = 200 mg. Carat (ct) is further divided into 100 points. The larger the weight, the larger the size of the diamond (Figure 1). The higher the weight of diamonds of the same quality, the more expensive they are. However, the price of diamonds does not increase in proportion to their weight. The price may increase by multiples.
Figure 1 The relationship between diamond weight and size
- Color
Figure 2 Diamonds of different colors
The general color grading method for diamonds is to classify diamonds into different grades according to the degree of yellowness, and compare the samples with master stones of known color grades, with D being the highest and Z being the lowest.
Colorless (a): D, E, F; nearly colorless (b): G, H, I, J; slightly yellow (c): K, L, M; slightly pale yellow (d): N, O, P, Q, R; light yellow (e): S, T, U, V, W, X, Y, Z. (Figure 3).
Figure 3 Diamond color
Among them, colorless (a), nearly colorless (b), and slightly yellow (c) are the most common diamond colors (Figure 4)
Figure 4 Diamond Color Grade Chart
- Clarity
Clarity: refers to the clarity of diamonds observed by a well-trained diamond grader with normal vision under a standard light source using a 10x magnifying glass. The clarity from high to low is: IF > VVS1 > VVS2 > VS1 > VS2 > SI1 > SI2 > I1 > I2. (Figure 5)
Figure 5 Diamond Clarity Grade
- Cut
Cut is the most important factor affecting the brilliance of diamonds. A perfectly cut diamond looks more dazzling. According to the cut of diamonds, from low to high, they are: POOR < FAIR < GOOD < VERY GOOD < EXCELLENT (Figure 6)
Figure 6 Diamond Cut Grade
The quality of diamonds is mainly evaluated comprehensively based on the above four different parameters. The higher the comprehensive grade, the more expensive the diamond will be.