Gemstone Education

The Gemstone 4 C's

Gemstone 101

An organic material or mineral that is mined from the earth is called a gemstone. Prior to gemstones being cut, polished and turned into jewellery, they are found to be asymmetrical and dull and are located in various locations and climates of the world. The terms “jewel” and “gem” are used equivalently however there is a distinct difference between the two. A gemstone in its rough form before being set into jewellery, is basically just a stone whereas once a gemstone is fashioned into a piece of jewellery, it can then be considered a jewel. Gemstones come in an array of brilliant colours and can be appreciated for their beauty and rarity.


Understanding the 4 C’s of Gems Shopping

Gemstones are not valued by their beauty, size, durability and rarity but the 4 C’s as well. What are the 4 C’s – Colour, Cut, Clarity and Carat Weight. These 4 factors assist greatly when the task of acquiring gemstones arise. Knowledge of the 4 C’s makes the whole process simple when choosing a gemstone.

Bear in mind that your personal choices may not confirm with industry standards where high saturation is a requirement whereas the stone of your choice may have less saturated colour. It is best to go with the gemstone that captivates your heart than the stone you think you should have.



The clarity of a gemstone is based on the visibility of its inclusions or if there are any strange inclusions in the actual stone. Basically, the fewer inclusions, the more valuable the stone and more inclusions depreciate its value and price. Most stones naturally have inclusions due to the way they are formed in the earth. Inclusions such as liquid, dust, insects, air pockets and other minerals are the foreign objects that can be found within a stone during its creation. Sapphires with inclusions that may look like a star which make the stone rarer, is an exception.

Gem Clarity Descriptions

Colored gemstones can have the following clarity grades:

  • VVS: very, very small inclusions
  • VS: very small inclusions
  • SI1 and SI2: small inclusions
  • I1, I2, and I3: included


The way in which a gemstone is styled to refract light and has been faceted is called the cut. Jewellers geometrically cut multiple flat facets into the gemstone to exaggerate a stone’s brilliance and not just its polishing and tumbling. There is a difference between the styling terms cut and shape which are often misinterpreted. The importance of utilising the terms cut and shape correctly by jewellers is crucial as there are certain cuts applicable to certain shapes. The general outline of a stone when viewed from above is referred to as shape, while the faceting of a gemstone to display its brilliance is referred to as cut. An example of this explanation is that the brilliant cut, which is very popular cut, is a style applicable on square, round and heart-shaped gemstones.

Gem Clarity Descriptions

List of cuts below:

Step; Brilliant; Ceylon; Rose; Cabochon; Barion; Checkerboard; Eight; Old Mine; Trillion and Princess Cuts

List of Shapes below:

Heart; Marquise; Emerald; Asscher; Round; Oval; Cushion; Baguette; Pear and Briolette


Gemstone Cuts and Facets

Step Cut: Used on baguette, emerald, and asscher gemstones, the step cut involves rectangular and square facets that create a deep, mirror-like look.

Brilliant Cut: A brilliant cut can be applied to round or square gemstones. It is one of the most popular cuts because of its intense sparkle. The brilliant cut has many variations based on the shape and size of the gemstone.

Ceylon Cut: A Ceylon cut is a combination of both step cuts and brilliant cuts. A Ceylon gemstone has a brilliant-cut crown and a step-cut pavilion.

Rose Cut: A rose-cut gemstone is faceted similarly to a brilliant cut, but has a flat bottom and consistent repetition of same-sized triangular facets over the entire crown. Their flat bottom makes them weigh less than other cuts.

Cabochon Cut: Cabochon gemstones are tumbled and polished until they reach a glossy shine. Then, they are cut to fit into particular settings, but otherwise left alone. Cabochon gemstones don’t have facets, and feature a smooth domed crown.

Barion Cut: A barion cut is a combination of a step cut and brilliant cut in the crown of a gemstone. It can be applied to square, rectangular, and round shaped gemstones.

Checkerboard Cut: A checkerboard cut is similar to a rose cut, but uses square facets instead of triangular facets to achieve a checkerboard look. This cut is common on cushion-shaped gemstones.

Eight Cut: The eight cut is a simplified brilliant cut, pared down to only eight facets around the crown.

Old Mine Cut: The old mine cut is the predecessor to the brilliant cut. Still faceted for ultimate sparkle, old-mine cut gemstones have a taller crown and larger facets than the traditional brilliant cut.

Popular Gemstone Shapes

Heart: The heart-shaped gemstone features the traditional romantic symbol with a modified brilliant-cut facet pattern to suit its unique silhouette.

Marquise: A marquise-shaped diamond has two curved edges that come to two opposite points. Like the oval, round, and pear shape, a marquise-shaped gemstone is faceted with a variation of the brilliant cut.

Emerald: Emerald-cut gemstones feature a flat table and are usually rectangular with step cuts and about 50 facets. An emerald cut has more of a “mirror” effect than a “sparkle” effect on gemstones.

Ascher: Ascher gemstones are simply the square version of an emerald cut, including the square and rectangular mirror-like step facets.

Round: The round gemstone is possibly the most popular shape, especially for classic solitaire settings. Round gemstones usually feature a brilliant, rose, or cabochon cut.

Oval: An oval shaped gemstone has an elongated round shape with a modified brilliant cut featuring more facets than the traditional round brilliant cut stones.

Cushion: A cushion-cut gemstone is a variation of the square or rectangle, with slightly curved edges and rounded corners.

Baguette: A baguette-shaped gemstone is a long, narrow rectangle and is often faceted with step cuts similar to emerald cuts.

Pear: Pear shaped gemstones have one rounded edge that comes to a single point, resembling the shape of a raindrop. This shape offers a vintage look and brilliant cut faceting that is modified to suit its shape.

Trillion: A trillion-cut gemstone is a three-sided, curved triangular gemstone averaging 31 to 43 facets.

 Princess: The princess-cut diamond is just as popular as the round brilliant cut and is very similar in brilliance. Up to 76 facets give this square-shaped gem a sparkle unlike any other cut.

Briolette: A briolette-shaped gemstone is similar to the pear shape, but it is faceted on all sides and cut to hang as a necklace pendant or drop earrings.


The most important value factor when purchasing gemstones is colour. Gemstones come in almost every colour possible and one gemstone can have various and numerous hues like tourmalines, sapphires and garnets which all come in pink, yellow and blue hues.

There are three categories in respect of a gemstone’s colour i.e. its hue, tone and saturation. Colour quality and cost are determined by these categories. The most wanted gems are the ones with intense hues and medium tones however you should go with your preferred choice of colour.

Gem Color Descriptions

Hue: The six primary hues are green, violet, yellow, blue, red and orange with secondary hues between these primary hues such as blue-green. The most valuable gemstones for eg. emerald, sapphire and ruby have pure primary colours whereas the less valuable gemstones are either very dark or pale or interrupted by brown and grey.

Tone: basically means the lightness or darkness of colour. Tones come in a variety of colours such as clear to black with a variation of hues i.e. clear or light toes in an emerald makes light green and a dark-toned emerald gives a deep-forest green. Tone is also known as value.

Saturation: is basically the amount of colour existing in the stone. An example of a perfect saturation is when a gemstone is flawless and deep like a ruby that gives a pure red colour and is not disturbed by traces of pink, orange and yellow or brown and grey tints.

Gemstone by Hue

A feature of gemstone colour is gemstone hue however factors such as tone and saturation aren’t included. While some gemstones are a single, primary hue, coloured gemstones can be found in numerous hues such as yellow, green, orange, red, violet and blue which are a variety of the six primary hues. Being a combination of primary hues, other coloured gemstones fall within the spectrum. Gemstones that include more than one hue such as tourmaline, opal and topaz. The most common gemstones by hue are listed hereunder:

Pink Hue: rose quartz, topaz, ruby, diamond, tourmaline

Red Hue: ruby, carnelian, coral, zircon, garnet

Yellow Hue: citrine, diamond, sapphire, garnet, peridot, amber

Green Hue: emerald, jade, malachite, alexandrite, topaz, zircon

Blue Hue: sapphire, zircon, lapis lazuli, turquoise

Purple Hue: amethyst, alexandrite, tanzanite, purple jade, opal, garnet

Black Hue: hematite, onyx, diamond, obsidian, beryl, pearl

Brown Hue: topaz, diamond, amber, citrine, smoky quartz

White Hue: diamond, pearl, zircon, moissanite, opal, moonstone

Carat (Size)

The standard weight measurement used is the carat which converts to one-fifth of a gram. The density varies from stone to stone as each stone comprises of a different mineral. It is the weight of a stone that matters and not the size. For instance, if you compare a one carat emerald to a one carat ruby, both with the same weight, the ruby being the denser stone will be smaller. One can expect to pay much more per carat for stones such as spinels; alexandrites; emeralds, sapphires and garnets as certain gemstones are rarely found in large sizes.

Gem Sizing Descriptions

Faceted gemstones are estimated in various manners, the most widely recognized estimation is carat weight. The worldwide standard of the metric carat was received in the United States by 1920 and this is the present standard for gauging gemstones. One metric carat = 0.2 gram (or 200 milligrams).

You’ll discover assessed loads for various sizes of faceted gemstones in the accompanying outline. Diverse gemstone materials have various loads, much the same as steel and block have various loads. For instance a carat of a light material, for example, opal will be bigger than a carat of an increasingly thick stone, for example, peridot or topaz.

Precious vs Semi Precious Gemstones

Each gemstone possesses a uniqueness and a distinct mineral content which contributes to its specific characteristics. Due to their rarity, accessibility, purity and sometimes their cultural significance, some gemstones are considered to be more valuable than others. Diamonds, rubies, sapphires and emeralds are perceived as the most precious gemstones due to their chemical content, the time involved to create them, their quality and rarity. Despite all other gemstones being categorised as semi-precious, majority of these are considered to be equally precious and rare as the 4 precious gemstones.

Precious Gemstones – having been utilised in cultural rituals during ancient times, precious gemstones have since been perceived to be more rare and valuable. They have very strong chemical content and generally pure in colour.

Semi-Precious Gemstones – These are not considered as having equal value as precious stones however just as rare in some instances. Semi-precious come in many primary and secondary hues, different chemical content and distinctive inclusions.


Organic and Mineral Gemstones

Organic Gemstones – commonly formed or harvested from the earth and sea, organic gemstones are derived from living organisms such as plants and animals. Pearl, amber and coral are the most common of organic gemstones.

Pearl: are organic gemstones that are found in both freshwater and saltwater oysters. A lustrous pearl is formed as the result of an oyster producing layer upon layer around the pearl particle. The oyster acts as a protective host to the pearl.

Amber: derived from the fossilized sap or resin of ancient and extinct pine trees and sometimes traps insects and other organisms such as plants within its translucent orange material. Being a rare, organic mineral, amber can also be found in colours such as brown, pink and gold.

Coral: is a skeletal structure found in water which similar to the pearl, is formed by small ocean animals. This organic gemstone is produced when the ocean animal coral polyps dies and what remains is a hardened skeleton which is then utilised for décor purposes and the production of jewellery.

 Mineral Gemstones – the different types of mineral gemstones undergo special individual combinations of pressure, heat and time in order to produce the hardened crystal bodies which are unique to the specific gemstone itself.

Diamonds: are the strongest known mineral in the world and a concentration of pure carbon either colourless or almost colourless. Diamonds are created under immense heat and pressure from deep in the earth and although though to be colourless, they come in various colours and shades.

Sapphires: formed as the result of extreme heat and pressure of aluminium oxide over thousands of years. Sapphires also come in various colours but the most valuable of these is the blue sapphire.

Rubies: are in fact sapphires i.e. aluminium oxide that has inclusions of the metal chromium giving it its deep red colour.

Emeralds: are made from Beryllium Aluminium which contains iron, vanadium and chromium which gives it its green colour.


Lab-created Gemstones vs Natural Gemstones

You can find precious and semi-precious gemstones in nature or formed in a lab. Natural and synthetic gemstones have no chemical difference, they look similar, come in the same colour and have the same quality. All gemstones possess their very own chemical and mineral content which can be reproduced in a lab to form genuine gemstones a lot faster than as that naturally produced by the earth.

Advantages of gemstones created in a lab

  1. Lab-created gemstones are produced more quickly as opposed to natural gemstones mined from earth and sea.
  2. Found to be more cost effective than natural gemstones which are extremely expensive.

Lab-created gemstones are identical to naturally produced gemstones.

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