How is a Ruby Cut

A ruby’s cut is one of the primary factors that determines it’s value as well as it’s overall beauty and appeal. The structure of the ruby crystal is the primary determinant in how it is cut. Rubies can be cut into many shapes and sizes. Various factors are considered when taking a raw ruby deposit and shaping ruby gemstones from it.


Shape and Carat

Most popularly, rubies are cut into a cushion and oval shape. The shapes of the rubies follow the same conventional shapes as that in a diamond. However, in most gemstones, more of the carat weight is retained at the bottom of the ruby. Therefore, a ruby that has the same carat weight will have a smaller millimeter when looked at faceup. This means that while that carat weight may be the same, the cut of the ruby will make it look visually smaller than a diamond of the same carat. This is especially true in the round shaped ruby. Round, cushion and oval rubies are very commonly used in pendants, rings and earrings. While the round shape is popular, it creates more rough wastage. For this reason, these shapes are available in a variety of sizes. Cutters also tend not to cut rubies in very small size as they can look very similar to a round shape. Learn more about Ruby Shapes.

Round red natural AAA quality Ruby
Oval red natural AAA quality Ruby
Cushion red natural AAA quality Ruby
Emerald red natural AAA quality Ruby

Other less common shapes include emerald, pear and marquise. While these shapes are commonly available in smaller sizes under a carat, it becomes increasingly difficult to find them in larger sizes. Another popular shape for a ruby is princess. This perfect square looks beautiful set in any kind of jewelry. However, as it is difficult to cut, it can de difficult to find it in very small sizes.

Overall, the goal then cutting a ruby is to preserve as much of the rough gemstone as possible. The rough gemstone is the raw ruby that is mined. Avoiding wastage and considering which shapes are popular are often the largest determinants in what size and shape the ruby is faceted into. Gemstones are typically cut into standard millimeter sizes for jewelry. These are referred to as calibrated cuts. While there may be more weight loss in creating calibrated sizes, they are more desirable when crafting jewelry. In special instances or for larger carat weights, rubies may be cut into sizes that deviate from the norm.


Color Consideration

Another important factor that is considered in the cutting process is the color, saturation and hue of a ruby. In all rubies, the primary color is red. However, all rubies do exhibit the appearance of different colors in tinges such as purple or orange. Rubies exhibit pleochrism. This means that depending on the way a particular ruby is cut the crystals can exhibit a purplish red or an orangey red. By positioning the table facet in a perpendicular direction to the long crystal, the ideal color can be achieved. The art of cutting a ruby and weighing all of these factors requires a trained eye. Color must also appear to be uniform across the entire ruby. Gems that have even color are considered to be more valuable. More information can be found in our ruby color guide.

Ruby Brilliance

The artful and precise faceting of a ruby determines how the light responds to it. Ultimately this is what determines how much sparkle or life the ruby has. The gemstone cutter should facet the gemstone in a way that the maximum amount of light is entering the gemstone and reflecting back out. If the culet, or bottom facet, is cut too large, the light will leak out of the bottom of the ruby. The angles of the facets determine how the light reflects within it. If the faceting is not symmetrical, the sparkle can be affected. Ruby cutters must precisely fashion a ruby to allow the most brilliance and fire to come through.

sparkling natural oval ruby showing light performance and brilliance

Types of Cuts

octagon step cut natural red ruby

Step Cut

A step or emerald cut has facets that run parallel to the ruby’s edge. Visually these step cut facets look like a symmetrical ascending staircase. The corners of the ruby are softened or rounded slightly to ensure that the corners do not chip or get damaged as the points are very small and sharp. This cut brings out the natural beauty of the red in the ruby.

round brilliant cut natural red ruby

Brilliant Cut

The brilliant cut are triangular cut facets that can vary in number depending on the shape of the ruby. The facets are cut symmetrically for the purpose of drawing light into the ruby. A brilliant cut round ruby will typically have 58 facets.

round mixed cut natural red ruby

Mixed Cut

The mixed cut is a hybrid of the brilliant cut and the step cut and is the most common cut for a gemstone or ruby. The crown of the ruby is typically brilliant cut to enliven the sparkle and the pavilion is step cut. This reduces the rough wastage and also helps the color of the ruby to shine through. Four Mine uses rubies that are brilliant cut or mixed cut to maximize the sparkle and color.

round cabochon cut natural red ruby

Cabochon Cut

Vintage jewelry styles can feature the cabochon ruby cut. In this cut the ruby has a domed shapes with a flat bottom. The top is smooth and not faceted with a highly polished surface. The cabochon cuts are the easiest to manufactures and typically less expensive.


Ruby Inclusions

Inclusions in a ruby are natural formations that occur as the ruby is being formed within the earth. Commonly these inclusions can look like silk, darker knots or cracks. When cutting a ruby, it is important to maintain the structural integrity of the gem. No cracks or fissures should be so large and visible as to affect the beauty of the final gem. Additionally, if inclusions can be seen when the ruby is viewed from the top, in the table the gemstone loses some desirability and value. The goal is to minimize the inclusions in the center of the ruby while also minimizing the waste of the rough ruby. Typically cutters will aim to produce rubies that are eye-clean to create the best value. Four Mine uses only eye-clean rubies in all jewelry. Learn more about ruby clarity.

ruby with natural crystal inclusions
ruby with many white feather inclusions
Needle Inclusions in rubies known as silk
several overlapping needle inclusions with crystals in a red ruby
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