Cut and Clarity

Clarity

Gemstone clarity refers to the internal (inclusions) and external flaws of a stone. A flawless coloured gemstone is a lot rarer than a flawless diamond. Although clarity is important, it is the location and type of inclusion which is crucial in coloured stones.  If the inclusion is small and positioned in a less noticeable area in the stone, then it will not affect the gem’s beauty or price as much as a prominent flaw such as a surface crack.

For example, because the natural process of emerald formation is aggressive, most emeralds, even the most expensive, have many flaws. Lighter gemstones do show their flaws easier than dark gemstones as the depth of their colour hides the defects.

Another important consideration is the location of the inclusion. A large crack on the surface of the stone can interrupt movement of light through the stone and also affect its durability. This can detract from the stone's beauty and reduce its market value. However, if the flaw is small and in a less noticeable area, beauty, price and durability are normally not affected.

Inclusions are often used to identify the origin of a gemstone, Sandawana Emeralds and Mogok rubies for example, have unusual crystal formations, and distinctive inclusions  that identify the stones as having these specific origins.

Yellow gold pendant with 8x8 cushion cut amethyst by Eska Claire

Buy this pendant from SHOP @ 67

Inclusions

Most inclusions are not visible with the naked eye, usually you need to use at least 10X magnification to see them. Larger ones can be seen with the naked eye. Inclusions can be an unfilled cavity, a small crystal, a fracture, or a growth pattern within the gem. There are 3 categories of inclusions:

Cavities:

Cavities are formed during the gemstone’s growth. They can be filled with combinations of liquid, gasses, or solids.

Growth Phenomena:
A few examples of this are solid crystals, natural glass, and limonite tubes (hollow channels stained by iron compounds).

Solids:

A few examples of this are solid crystals, natural glass, and white mica inclusions.

Here is a table that lists the basic inclusion frequency in common gemstones.

Touchstone uses the following clarity scale when grading gemstones:

Cut

TOUCHSTONE carries the following Standard Calibrated Shapes in its current inventory (In addition to 39 fancy cuts:

	Round		Marquise
	Oval		Trillion (Trilliant)
	Square (Carre)		Baguette
	Octagon (Emerald)		Heart
	Pear		Princess Square

Gemstones can be cut with or without facets.  Gemstones are more commonly cut with facets and the position of the facets is carefully planned to ensure that the largest amount of light is reflected within the gemstone’s body. By doing this, the stone's best colour and brilliance will be displayed. The way a stone is cut probably has the greatest impact on the stone's beauty. The most popular fashioning methods of coloured gemstones may be divided in four categories:

• Brilliant
• Step
• Mixed
• Cabochon (facet less)

The cabochon cut is a facet less cut that produces a rounded dome shape with a smooth surface. In olden times, cabochon gems were popular due to their stronger colour.  These cuts are now gaining popularity again, as many people prefer the more subtle, softer look of the cabochon.

Brilliant Cuts

The brilliant ensures that maximum light is reflected out through the front (table) giving brightness and fire.  This cut has many facets which heighten light refraction making it the most popular cut. Oval produces a larger appearance from a smaller carat weight.

Step Cuts

Otherwise known as the “emerald cut”, this cut intensifies a gemstone’s colour.  Variations are square, octagon, some ovals, baguette, and other table cuts.

Mixed Cuts

Mixed cut stones are usually brilliant cuts with the pavilions step-cut. Sapphires, rubies and the majority of transparent colour gemstones are cut in this style. Cut variations include cushion, pear or teardrop, plus some oval cuts.

Cabochon

Translucent or opaque gemstones like opal are polished rather than faceted.  This cut can also produce cats-eye and star effects. Sometimes, gemstones with lots of inclusions are cut in a cabochon cut to hide them.  Cabochons have a smooth, rounded surface with no facets. The bottom of the stone is flat or nearly flat.