Understanding Gemstones

The allure of precious stones lies in their colour, tone, saturation, inclusions, character and clarity, which skilled artisans carve into exquisite jewellery. Choosing a coloured precious stone means appreciating millions of years of Earth's history and thousands of hours of craftsmanship. Along with colour, cut, clarity and carat weight, one must also consider a precious stone's symbolism, values and personality, which are captured by the six Cs, including certification and character. While personal preferences may lead to deviations from expert opinions, emotions cannot be measured by these guidelines.

CUT PROPORTIONS AND LIGHT

The cut proportion of a precious stone refers to its shape and dimensions, including the depth, angles and symmetry of its facets. The way a precious stone is cut can greatly affect its overall appearance, as it impacts the way light interacts with the stone.

When white light enters a coloured precious stone, some of its rays are reflected outward while others are absorbed into the gem, creating its body colour. The transmitted rays are then returned to the viewer's eyes.

3 DIMENSIONS OF COLOUR

Colour consists of three aspects: hue, tone and saturation. When dealing with transparent precious stones, it is useful to think of colour in a 3D system. The most desirable precious stone colour would be located at the "equator of the globe" with a medium tone and high saturation.

PLEOCHROISM

Pleochroism is a gemological term used to describe a doubly refractive gem that exhibits different colours when viewed from different angles. Tanzanites are examples of such gems. A lapidary with excellent skills can cut the gem in a way that reduces the pleochroism effect in the final cut and polished gem. The goal is to create a gem that displays the full colour when viewed face up, with minimal or no secondary hues.

The Four Cs of Gemstone Quality

Just like diamonds, colored gemstones are often evaluated by four key characteristics:

Color – The hue, tone and saturation of a gemstone determine much of its beauty and value.
Clarity – Refers to the presence (or absence) of inclusions or blemishes within the stone.
Cut – A precise cut enhances brilliance and symmetry, maximizing the gem’s visual appeal.
Carat Weight – Larger stones are rarer and therefore more valuable, but color and clarity also play significant roles.