Houston Jewelry Appraisal and Repair

Colored Gemstone Cuts and Proportions by GIA

CUTS AND SHAPES

Colored stones are fashioned, or cut, into all kinds of creative patterns and shapes. Their facets can have many different arrangements.

The hardness of a mineral is always considered before cutting (refer to the mohs scale of hardness.)

It is more difficult to cut and polish Sapphire than it is Quartz. All minerals have their own challenges when it comes to cutting. Additionally, cutters are also confronted with unique inclusions; making their job demanding.

Here are some of the different cuts used for colored gemstones:

Brilliant Cuts- triangular and bezel, or kite-shaped facets (most common in calibrated stones)

Step Cuts- gems containing square and rectangular facets

Mixed Cuts- a gemstone comprised of brilliant and step cut facets

Cabochon Cuts- domed surface or top with a flat or rounded base (most commonly seen in aggregates and phenomenal gemstones like Opal)

Designer Cuts- patented, checkerboard, and unique signature cuts (commonly seen in designers like Konstantino, Yurman, and Hardy)

Fantasy Cuts- free-style cuts that give way to creative shapes

Cameos- images or designs sculpted to protrude from the surface of a stone

Intaglios- designs carved into the surface of a stone

Manufacturers will tend to cut gemstones in order to preserve weight. For instance, when a cutter
receives a gemstone, he or she may be told to maximize the carat weight. Therefore, this will tend to become priority over color and clarity.

Take color for instance. After the stone is cut, they may render a ten carat total weight gemstone, but it may be very dark in tone due to its deep pavilion. Though the carat weight is ten carats, recutting the stone below ten carats to 9.50ctw may actually improve its color.

For the most part, this will also create a much larger demand for the gemstone, increasing its value. The market price is usually compared before the recut process is initiated. It is not suggested to recut the stone's price does not increase.

GEMSTONES

DEEP CUTS

Stones with deep pavilions lack vibrancy. Because they are cut deep, they are usually very dark in tone. This is due to the adverse cut angles and its pavilion bulge. It causes *extinction and hides color. Gems can be recut to produce a medium to medium dark tone; restoring vitality.

*Extinction- seen in deep gemstones; the gem leaks light and displays dark, black areas that embody it.

GEMSTONES

SHALLOW CUTS

Shallow gemstones cannot be recut. Too much weight would be lost to produce angles sufficient enough to show more color.

They can also exhibit *windowing; a negative characteristic. Yet, sometimes manufacturers will deliberately cut a gem shallow to lighten a dark stone; in turn displaying more color.

Even more importantly, a shallow stone is more prone to break if accidently stuck on something because it is thinner.

*Windowing- usually seen in shallow gemstones; this is an area in the stone that lacks color concentration, allowing you to see right through it.

Polish and Symmetry are other elements to consider.

Only a master gemologist can grade and assess cut angles, depths, symmetry and polish in colored stones.