SUWA

BEAUTY GRADE: ELEMENTS AND JUDGMENT

Using sapphire as an example, let us explain the elements of the beauty grade for gemstones as a whole. The beauty grade ranks the degree of beauty based on a combination of the following eight elements. The beauty grade may be lowered by any one element or by the combined influence of a number of elements.

The sapphire shown immediately below is an attractive gemstone with no major imperfections that detract from its beauty.

1. Hue

This sapphire’s color is somewhat reddish compared to the one above. While the hue in this particular stone is shifted toward blue-purple, color in sapphire may also shift in the opposite direction and become slightly greenish. Hue may be a characteristic of the country of origin, or it may be related to tone. It is a key point when judging.
2. Transparency
(Nature of Rough)

Compared to the one above, this sapphire has a low transparency level and is somewhat cloudy. Even if other conditions are basically the same, transparency can greatly affect the beauty of a gemstone as well as its value. This applies to diamonds as well as colored stones.
3. Saturation (Purity of Color, Grayness, Brownness)

This sapphire is a very grayish blue. Such grayish color (or brownish color in red to orange gemstones) is not uncommon. Stones with a pure color are said to have high saturation, and those with a strong grayish or brownish color, to have low saturation.

4. Degree and Direction of Pleochroism (Doubly Refractive Minerals Only)

This sapphire shows purplish and green hues besides the blue. This is influenced by the quality of the rough, as well as the position of the table relative to the optic axis of the stone. Pleochroism detracts from the beauty of a stone.
5. Appearance and Shape (Outline, Finish, Profile, and Proportion)
This sapphire is very thin and flat, and its color is almost completely washed out. The beauty of the mosaic-like pattern of facets is absent, and a blue color is visible only around the edge of the stone. This stone does not even qualify as accessory quality, and should be rejected.
6. Windowing, Uneven Color, Richness of Color

Two zones of blue color and three colorless areas can be seen near the center of this stone. Uneven color results from a complex interaction between the location of color in the stone and how the stone is cut, while the richness of color depends on the fineness of the rough material.
7. Inclusions (Internal Characteristics)

A round shape can be seen near the top of the table surface. This is an eye-visible inclusion, and it affects the beauty grade even in colored stones. It is necessary to confirm the presence of inclusions by varying the lighting, method of viewing, and the viewing angle while examining the stone under magnification.
7. Fluorescence

The fluorescence seen in certain rubies, diamonds, and other gemstones is an element that can either enhance or detract from a stone’s beauty.

JUDGING QUALITY

Sapphires with a tone of 5, a high level of transparency, and a brilliant quality are considered attractive. Sri Lankan material fits this description, and in this regard it is superior to stones from other sources.

When viewed under weak lighting, small sapphires appear blackish. Beauty will particularly suffer in stones with a tone higher than 6 if their transparency is low. In fact, under poor lighting conditions a tone of about 4 will appear more attractive. In the west, darker stones tend to be preferred, and prices for these may be high-but, a high price cannot be justified is a stone’s transparency is poor.

In one-carat sizes, dark blue (tone7) sapphires will not shown an attractive mosaic pattern, but in larger gem-quality sapphires, refraction and reflection caused by the facets create a mosaic pattern of deep and light blue. For large sapphires with tone 7, such as those from Myanmar, it is important to judge quality based on the fineness of the balance of the mosaic pattern.
 
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