About Gems and Jewelry
What are gemstones?
For centuries, we have been fascinated by this wonderful creation of mother nature. Gemstones have always been a symbol of wealth and beauty. The term Gemstones means any mineral or organic material, used for personal adornment, display or object of art because it posses beauty, durability and rarity. From the many hundreds of minerals found only a few posses all the three quality.
What makes Gemstones valuable?
The degree of presence of these three qualities, like beauty, durability and rarity makes the gemstone valuable.
Beauty of a gemstone is the combination of the color of gemstones, clarity and various optical properties.
Durability of a gemstone refers to the hardness of a gemstone. Rarity of a gemstone is the difficulty in finding and cutting the gemstone in appropriate size and shape.
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.
Idio-chromatic 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
- Talc - Talc is the world's softest mineral and the lowest mineral on the Moh’s scale.
- Gypsum - Gypsum is a soft mineral composed of calcium sulfate dihydrate.
- Calcite - Calcite is an anhydrous carbonate, and one of the most widely distributed minerals on the Earth's surface.
- Fluorite - Fluorite (fluor-spar) is a mineral composed of calcium fluoride.
- Apatite - Apatite (hydroxylapatite, fluorapatite, chlorapatite) is a group of phosphate minerals and is one of few minerals that are produced by biological organisms.
- Orthoclase - Orthoclase (aka feldspar) in an igneous rock forming tectosilicate (silicate) mineral and is a key component in granite.
- Quartz - Quartz is one of the most common minerals found in the Earth's crust.
- Topaz - Topaz is a silicate or "nesosilicate" mineral created from a combination of aluminum and fluorine.
- Corundum - Corundum is the crystalline form of aluminum oxide and one of the basic rock-forming minerals.
- 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.
What are the different shapes of gemstones?
Gemstones are cut in different shapes, depending on the size and shape of the rough.
Some of the most popular shapes are as follows:
What are the different parts of a gemstone?
A cut a polished gemstone can be divided into five parts, namely Table, Crown, Girdle, Pavilion and Culet.
Table is the biggest facet of a gemstone. This is the top facet and this is the facet that is the most visible after being set in jewelry.
Crown is the portion of the gemstone, which connects the table to the girdle. This portion has a lot of facets on it.
Girdle is the point which connects the pavilion to the crown. This is also the area where metal holds the gemstone in jewelry.
Pavilion is the portion that extends from girdle to the culet.
Culet is the last and smallest facet.
What is an inclusion?
Inclusions are present in almost all of naturally occurring gemstones. These are caused due to various reasons. As the host rock forms in the crust of earth, there are a lot of other factors happening to the host rock or the mineral forming with the host rock. These factors cause impurities in the mineral. These impurities are called inclusions.
An Inclusion can be gas, liquid or solid enclosed within the gemstone. In gemstones, inclusion also applies to cleavage, cracks, fractures, growth lines, color zoning and crystals of same or different mineral. Some of the major types of inclusions are as follows:
Bubbles: These inclusions resemble bubbles of various shapes and sizes.
Clouds: Groups of fine bubbles or cavities.
Color Zoning: When the color is not evenly spread in the gemstone it is called zoning.
Feather: These are internal cracks in the gemstone.
Needle: These are inclusions, which are long and thin like the needle.
Fingerprint: These are inclusions which look like a fingerprint or a maze.Silk: These inclusions are needle like crystals, which intersect ea