Jewelry Information

Introduction

Diamonds

Colored Gemstones

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Colored Gemstones

Introduction

Emerald

Ruby

Sapphire

Other colored gemstones

Colored Gems - the 4 Cs

  Color

  Cut

  Carat

  Clarity

Colored Gem Certificates

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Colored Gemstones - Cut

Shaping the Stone

Gemstones are cut to show them to best advantage. For many richly colored stones, a smooth rounded shape or a flat polished surface does this best. Indeed, cabochon is the oldest gemstone cutting.

moonstone

jade

malachite

 

Transparent gems, such as emerald and ruby, are usually faceted to show them to best advantage.

emerald

garnet

amethyst

 


In faceting, planes are cut into the surface of the stone. The purpose is to let light pass through and be reflected and refracted from faces on the back of the stone.

These are some of the many shapes for faceted gems (top and side views).

Round Brilliant Cut

Emerald Cut

Baguette Cut

Marquise Cut

Oval Cut

Flanders Cut

Princess Cut

Pear Cut

 

The shape of a gem should not be confused with its cut, or cut proportions. Shape is a matter of taste and style of jewelry, but cut is one of the “4Cs” that determine a gem’s value.

Cut Proportions

The diagram shows the facets of a round stone, viewed from the side.


When light strikes a faceted gem, it reflects and refracts on the faces of the stone, and returns to the viewer’s eye. The faceted cuts are precisely designed to show off the gem. Poorly proportioned gems retain more weight but their sparkle and richness of color are diminished.

In faceting, waste is unavoidable. For a well cut gem, the average weight loss from the rough stone is about 50%. Many stones are poorly cut to retain weight, because carat weight is what most buyers value. But a well proportioned gem has a higher value than a poorly proportioned gem of similar weight.