What is a Precious Gem Stone?

We have all heard the term,'Precious Gems', before but what, exactly, does it mean?

What makes one thing a precious gem stone and another a semi-precious gem stone or just a rock?

The answer to what makes a gem a precious stone is mostly historic and largely arbitrary.

It was determined by three key factors:

• Beauty or appearance: The precious gems historically included only the brilliant faceted gems like the diamond. Other gems, such as jade, ivory and turquoise, though beautiful in their own right, were not considered precious gem stones.

• Usage: The fact that the gem had a special religious or ceremonial significance allowed it to be classed as a precious stone.

• Rarity: The law of supply and demand is as old as it is universal. For a gem to be considered a precious stone, it must be historically difficult to come by. This factor has changed over the years as new sources of precious gems are discovered and new mining techniques are developed.

What gem stones are considered precious stones?

First of all, in modern gemology parlance, there is no distinction between precious and semi-precious stones. All stones are considered precious gems by the professional gemologist.

That being said, the classification of stones as precious gems has existed for thousands of years, and is still a concern of collectors.

There are only five stones that were historically considered precious gems:

• Precious Gem Stone 1 - The Diamond:

  Made of a crystalline form of carbon, the diamond is the most well known, and arguably the most admired of the precious gemstones.

  The word diamond comes from the ancient Greek word adamas, meaning 'impossible to tame'. The English word 'adamant', which means unbreakable or unyielding, comes from the same root.

  Diamond gem stone is the hardest naturally occurring substance, making it the most durable of all precious gem stones. The diamond's complex crystalline structure lends itself to multifaceted shapes, also refracts and disperses ambient light, giving it a brilliance that is virtually unmatched among the precious and semi precious gems.

• Precious Gem Stone 2 – The Ruby:

  Almost as well known as the diamond, the ruby gemstone also rivals the diamond for hardness, ranking nine on the ten point Mohs hardness scale.

  This precious gem stone is a crystalline compound based on the mineral corundum (aluminum oxide) mixed with the metal chromium, which produces the distinct and signature red color.

• Precious Gem Stone 3 – The Sapphire:

  A close cousin to the ruby, this precious gem stone is also based on corundum. While the blue sapphire gemstone is the best known variety, this precious gem stone comes in a range of colors (fancy sapphires) including pink, orange, purple, yellow, blue and white. In its most pure form, the sapphire is transparent.

• Precious Gem Stone 4 – The Emerald:

  Based on the mineral beryl, the emerald gemstone is pound for pound the most valuable gem stone in the world. The characteristic green color of this precious gemstone is caused by traces of chromium and iron.

• Precious Gem Stone 5 – The Amethyst:

  This precious gem stone is a variety of the common stone quartz. Its typical purplish color is caused by a combination of mineral impurities and crystalline structure. The stone known as burnt amethyst is created by heating the gem, producing a yellowish tint.

So again, what makes a gem a precious stone?

The answer is like the old adage, "Something is worth whatever someone will pay for it."

If a stone is precious to you, it is a precious gem stone, regardless of the comments of history.