Hi
From all these years of working with jewelry, it always fascinated me that why, some stones called gemstones and others are not? So my search for what is a gemstone, led me to speak with a lot of gem experts, countless hours on the internet and after reading a lot of books, I was able to put together this. I hope you all enjoy this.
A gemstone can defined as a mineral specimen that possesses three qualities, beauty, durability and rarity.
What is beauty of a Gemstone?
When we talk about the beauty of a gemstone, we refer to a combination of many different attributes. The first and foremost is the color, other features include clarity and other optical features.
Color: All minerals contain certain elements because of which they exhibit different colors.
Actual color of gemstone occurs due to the absorption and reflection properties of various elements and impurities present in the mineral. Gemstone color is either idiochromatic, allochromatic, or pseudochromatic.
Idiochromatic coloration is due to the inherent chemical makeup of the mineral, these are also called self colored because the arises due to the inherent chemical.
Allochromatic coloration is due to the presence of impurities within a mineral’s chemical makeup
Pseudochromatic coloration is caused by surface or subsurface reflective properties of the mineral
Color saturation: It takes several years, sometimes hundreds of years for mother nature to form a gemstone. The color of Gemstones is not always evenly saturated, because the color saturation depends on many factors like, pressure, temperature, and chemical concentrations. These factors can cause irregularity, color banding and zoning as the mineral crystallizes.
Clarity: Due of the nature of formation of minerals, a lot of minerals will contain impurities which can be seen with naked eye or with the help of a magnifying loop, these impurities are called inclusions. These impurities not necessarily decrease the value of the gemstone. Gemstones, where you cannot see inclusions with the naked eye are called “eye clean” Gemstones. Gemstones, where you cannot see inclusion with a ten time (10X) magnifying loop are called loop clean.
Optical features: These features play a very important part in determining the value of the gemstone. Some light will get reflected of the surface of the gemstone, the amount and the angle of light off the surface affects the luster of the gemstone. Some light enters the gemstone through the surface and gets refracted, scattered, and dispersed as the light exits the stone. As a light beam passes through a gem it is bent or refracted before it exits the crystal. The light beam is also broken into its component parts (dispersion) causing the effect known as "fire". This dispersion widens the beam to the point that the observer can see the full visible spectrum of the beam from red to violet, simulating a rainbow effect. As the stone is moved, the refraction and reflection points of the facets change showing the stone's scintillation or "play of color."
What is Durability (Hardness) of a gemstone?
Durability of a gemstone is the measure of hardness of a gemstone. Hardness of the gemstone is defined as the ease with which the surface of the gemstone will scratch or the gemstone will break. In gemstone industry, this term is measured by Moh’s hardness scale.
The Moh’s scale was invented in 1812, by the German mineralogist Friedrich Moh’s. Moh’s based his scale on ten minerals. Moh’s scale of mineral hardness quantifies the scratch resistance of minerals by comparing the ability of a harder material to scratch a softer material. With the Moh’s Scale, the hardness of a material is measured against the scale by finding the hardest material that it can scratch, and/or by identifying the softest material that can scratch it.
Minerals in order of hardness on Moh’s Scale
1. Talc
Talc is the world's softest mineral and the lowest mineral on the Moh’s scale.
2. Gypsum
Gypsum is a soft mineral composed of calcium sulfate dihydrate.
3. Calcite
Calcite is an anhydrous carbonate, and one of the most widely distributed minerals on the Earth's surface.
4. Fluorite
Fluorite (fluor-spar) is a mineral composed of calcium fluoride.
5. Apatite
Apatite (hydroxylapatite, fluorapatite, chlorapatite) is a group of phosphate minerals and is one of few minerals that are produced by biological organisms.
6. Orthoclase
Orthoclase (aka feldspar) in an igneous rock forming tectosilicate (silicate) mineral and is a key component in granite.
7. Quartz
Quartz is one of the most common minerals found in the Earth's crust.
8. Topaz
Topaz is a silicate or "nesosilicate" mineral created from a combination of aluminum and fluorine.
9. Corundum
Corundum is the crystalline form of aluminum oxide and one of the basic rock-forming minerals.
10. Diamond
Diamond is the hardest natural occurring material. Diamond is a natural allotrope of carbon.
What is Rarity of a Gemstone?
Natural gemstones cannot be produced in a laboratory and we have to rely on mother-nature to produce them. It takes several years sometimes hundreds of years for a gemstone to form. Availability of the gemstones also depends on the specific formation of minerals, which is effected by the temperature, pressure and chemical composition of the region. The availability of rough of the gemstone, the size of the rough found and, adds to the rarity of the gemstone.
What is Carat wt.?
The unit of measurement used to weight a gemstone is called Carat – with a “C”. It is not to be confused with karat – with a “K”, which is used to denote the percentage of pure gold.
One Carat is equal to one fifth of a gram, 1Ct. = 0.20gms. or 5 Cts. = 1 Gms.
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