Although gemstone trading dates back thousands of years, it wasn’t until medieval times that trade in gems became organized and secretive.
Secrets of the trade were passed on from generation to generation and are still evident today. It was essential for merchants to guard the source of their precious finds as a matter of self-preservation.
Today, the gemstone trade is a closed fraternity based on high levels of trust between members. Trust is the cornerstone of the professional jewellery and precious stone business. Gem buyers depend on honest information from trusted dealers with a gemological background. But in a world of enticing colours and glitter, the paths are fraught with deception and misrepresentation.
Just as in any other field, human ingenuity has entered the realm of gemstone enhancement, by artificially improving the appearance of the natural crystal. Heating or irradiating certain stones to saturate the colour may increase their values, while an untreated naturally beautiful sapphire or aquamarine will be traded at a premium. Industry standards mandate full disclosure of any enhancement a stone has been subjected to. This transparency is vital to the trade, from the gem dealer down to the consumer.
It is fascinating we value coloured rocks, formed in the earth’s crust over thousands or even millions of years of heat and pressure. Our lust for these sparkling beauties goes far beyond the physical properties we endear. Gemstones, in particular coloured gemstones, also boast the attribution of rarity and healing power.
While the business behind the gemstone trade is intriguing, our imagination is very much captured by the beauty and brilliance each crystal holds. Bringing this magic to light is the work of a very experienced lapidary (gem cutter), trained in various crystal systems and physical properties. This work is still done by very skilled hands and eyes to preserve the integrity of the most valued gems. Creativity and the advent of computer applications have also helped bring very effective new facet designs to light.
Precious stones are graded for value by a set of criteria known as the 4C’s:
CUT, COLOUR, CLARITY AND CARAT
One could arguably add the characteristic of rarity to this formula.
THE 4C'S ARE DEFINED AS:
CUT of a stone describes the geometry and placement of facets and the shape refers to the actual outline. The shape of gemstones plays a dominant role in any jewellery design. Classic shapes like round, oval and teardrop top the list, followed by emerald cut, square and cushion. The curved triangular form called trillion is considered one of the fancy cuts and is very versatile in jewellery design.
COLOUR may be the other preferred criteria when choosing a stone, as colour has the power to evoke deep emotional reactions. Hue is technically the colour, saturation refers to the brightness of the hue, either vivid or dull. Tone describes the hues lightness or darkness. Balancing the three factors in a gemstone creates the beauty we desire and love.
CLARITY indicates the level of blemishes or fractures contained within a crystal. Inclusions of any kind reduces the amount of light refracted and thus the stone will appear less brilliant. On the flip side, inclusions can be used very creatively as an original feature of the stone design.
CARAT is easily understood, as it specifies the weight of the gem. A metric “carat”
is defined as 200 milligrams.
A FEW LESSER KNOWN FACTS ABOUT GEMSTONES:
Sapphires are second only to diamonds in hardness and come in most hues of the colour spectrum.
A red sapphire containing a trace amount of chromium in its mineral composition is considered a ruby.
Emeralds and aquamarine are members of the beryl family. Also included in this group are red beryl, yellow (heliodor) and morganite.
Alexandrite is a chrysoberyl that has aluminium replaced by chromium. This composition enables the rare stone to change colour from emerald green in daylight to a strong purplish red in incandescent light.
Spinel gained prominence when, in the 19th century it was discovered that the Black Prince’s ruby was actually a superb red spinel. The stone is now part of the British Imperial State Crown.<