The 4 C’s of Gemstones:
When shopping for gemstones, you will encounter the four C’s. To clarify, the four C’s were established by the Gemological Institution of America (GIA) between the 1940’s and 1950’s. Further, this explains the four main valuation factors that affect a Diamonds price. After that, this gives the general public a better understanding of gemstone grading. As a result, the four C’s apply to Coloured Gemstones, too.
Size Does Matter
The weight of gemstones is measured in carats. To clarify, 1 carat (ct) is equivalent to 0.2 grams (g). In addition, carat weight is not the only way to measure gemstones. For instance, because of gemstone differences in gravity and density, not all gemstones that have the same carat weight share the same dimensions. In addition, the dimensions of gemstones are typically measured in millimeters (mm). More importantly, in nature, larger gemstones occur less frequently than smaller gemstones. Therefore, the rarity of large sized gemstones increases its price per carat.
Shaping It Up
The cut and shape of gemstones refers to the outlining shape and the quality of the cut. However, gemstones exist as shaped and faceted. On the other hand, gemstones also exist as Cabochons. Cabochons portray smooth surfaces with no angular facets. A well-cut gemstone will have good symmetry, defined facets and smooth surfaces. Well-cut stones will have minimal colour zoning. To clarify, this means that the gemstones have smooth, consistent colour because of light dispersion. On the other hand, an inferior cut gemstone looses colour because of poor light dispersion through the stone.
An Intricate Element
Think of clarity as nature’s way of leaving its fingerprint on a gemstone. For instance, inclusions are formed during crystal growth because of mineral impurities in the ground. A clarity grading looks at the number of inclusions that a gemstone has and its levels of transparency. However, for many gemstones, a clean clarity is favourable as inclusions found within the stone may compromise its colour and sparkle. In addition, gemstones can be found in transparent, translucent and opaque forms. Most importantly, some gemstones (Emerald and Red Beryl) naturally have low clarity. But, even so, these gemstones are high in price and value. Therefore, gemologists consider gemstones’ unique inclusions when determining prices.
A Very Subjective Field
The colour of gemstones depends on how it absorbs and reflects light. Carat size, cut and clarity gemstone gradings are easier to define than colour. Ways in which a gemstone’s colour is seen can significantly affect the value of the stone.
A well-known institution, Gemological Institute of America (GIA) recognizes over 30 gemstone colours and hues, 10 gradations in tone (from light to dark), and 6 specific levels of colour intensity (from neutral to vivid). It is common for gemstones to possess up to two or three hues which may be visible at the same time.
Evaluating gemstone colour in the following three ways:
- Hue – Hues refer to the most dominant colour seen.
- Saturation – Saturation is the intensity of the dominant colour seen.
- Tone – Tone explains how light or dark the colour appears. However, no two people see and appreciate colour in the same way. As a result, the colour of gemstones is personal.
Our Gemstones Are Measured In Millimetres
Gemstones are typically weighed in carats. 1 ct = 0.2 grams (g)
We offer a wide range of gemstone cuts
Colour plays an important role in gemstone grading. After that, the clarity of the gem is considered. On the other hand, clarity grading refers to the number of inclusions of a stone and its levels of transparency which can affect its durability and appeal. In addition, many gemstones have unique, natural characteristics. But, in some instances, inclusions are desirable. Moreover, there is no official, standard grading system that can be applied to all gemstone varieties.
Therefore, it is important to understand how gemstone clarity is evaluated. Firstly, before transparent gemstones are evaluated and given a final grading, they are examined based on what type of gemstone variety it classifies as. To clarify, this is because each gemstone variety has its own range of what is acceptable, regarding clarity and inclusions.
The Gemological Institution of America (GIA) groups coloured gemstone varieties into the following categories:
Type 1 Gems:
Gemstones like these are generally eye clean, meaning that no visible inclusions can be seen with the naked eye. In addition, type 1 stones include Amethyst, Aquamarine, Morganite and Tanzanite.
Type 2 Gems:
These types of gemstones usually have few inclusions. However, they can also be eye clean to a certain extent. The stones have minor inclusions which are visible yet are still desirable for jewellery pieces. For instance, Ruby, Sapphire, Alexandrite, Garnet and Peridot.
Type 3 Gems:
Gemstones as such almost always have inclusions. However, the rarity and uniqueness of the inclusions are in demand and have a high value. For instance, Emerald, Watermelon Tourmaline, Red Beryl and Rubellite Tourmaline.
Stones that are not faceted (such as Cabochons) are graded differently to faceted gems. Furthermore, the clarity of these types of gemstones are considered using the following:
- Transparent: These varieties allow light through the stone. As a result, objects behind the gemstone to be seen.
- Translucent: The structure of the gemstones allow a certain amount of light through the stone.
- Opaque: Gemstones as such do not allow light through the stone.
GeorGems uses the following clarity grading when evaluating our gems:
- IF – Internally Flawless Clarity – The stones are free of inclusions and blemishes found within and on the surface of the gemstone.
- VVS – Very Very Slightly Included Clarity – These gemstones are almost Loupe clean. Slight microscopic inclusions only seen with Loupe’s x10 magnification.
- VS – Very Slightly Included Clarity – Stones like this contain slight pinprick inclusions; they can only be seen with a well-trained naked eye.
- SI – Slightly Included Clarity – Inclusions are visible to the naked eye, but less visible at arm’s length. As a result, these inclusions cannot be seen without the x10 magnification of a Loupe.
- I – Included Clarity – The gemstones are included and can be seen at half an arm’s length with the naked eye.
- Transparent – Transparent gems allow light through the stone. As a result, objects behind the gemstone can be seen.
- Translucent – This variety only allows a certain amount of light through the stone.
- Opaque – Opaque stones do not allow light through the stone.
|Gemstone Name||Hardness||Gemstone Name||Hardness|
|Cat’s Eye – Chrysoberyl||8.5||Rhodonite||6.0|
|Cat’s – Quartz||7.0||Ruby||9.0|
Everything You Need To Know About Gemstone Treatments:
Many gemstones today are treated with various techniques in order to enhance the stone and to improve the clarity and to permanently change its colour. In addition, these treatments are widely accepted and recognised within the gemstone industry. However, unaccepted treatments are those that do not have a permanent effect on the stone.
At GeorGems, we inspect all gemstones and clearly state all treatments and enhancements that the gemstones may have gone through. In addition, all known treatments will always be listed on an item’s information page. In addition, below, we have provided you with some of the most common treatments that gemstones undergo:
Heat treatment –
Heat treatment is an acceptable and natural treatment for gemstones to endure. As a result, this is because it is seen as an extension of the heat treatment that the gemstone experiences when it originally formed in the Earth. Gemstones are heated to 1600°C. To clarify, this form of heat treatment dissolves inclusions and other small impurities and may cause the gemstone to change colour. Firstly, changing the colour or improving the clarity of a gemstone is permanent and irreversible. Moreover, heat treatment does not necessarily depreciate the value of a gemstone. However, the price of gemstones such as Tanzanite, Morganite and Zircon increases when they are heated.
Here is a list of commonly heated stones and the effect that the treatment has on them:
|Tanzanite –||Tanzanite heated makes a more desirable rich blue or electric violet colour.|
|Morganite-||Morganite is heated to change its colour from a peach-brown to a pink-orange or pink.|
|Ruby-||Ruby is heated to reduce to amount of inclusions and fractures and improve colour.|
Zircon is heated to produce blue, colourless and red stones.
Amethyst is heated to deepen violet colours, or to produce a yellow colour stone (Citrine).
Beryllium treatment –
Beryllium treatment (BE Heat) adds the element of beryllium to the heating process. To clarify, this is an acceptable form of heat treatment that is commonly applied to Sapphire. In addition, beryllium forms part of one of the most significant components of the Beryl gemstone family; Aquamarine, Morganite and Emerald. Beryllium heat treatment on Sapphire produces an array of colours. For instance, Yellow and Orange Sapphire. However, this heat treatment is permanent. Moreover, the treated gemstone may be re-sized. But, the colour will remain the same.
Fracture-filling treatment –
Small cracks or inclusions found within a gemstone causes light to pass incorrectly through a stone. As a result, the gemstone will have dead spots. But, if small cracks or fractures reach the surface of the stone, they can be filled. After that, light will be able to pass through. Glass or oil fills the cracks or fractures. In addition, Emerald often undergoes oil treatment as they are naturally included stones. On the other hand, Ruby often undergoes heat treatment and glass-fill treatment. As a result, the colour and clarity of Ruby improves. Therefore, this allows for larger sized, more affordable Ruby stones.
Irradiation treatment –
Exposing a gemstone to electrons from a linear accelerator refers irradiation treatment. For example, Blue Topaz often undergoes this process. As a result, this treatment produces the Sky Blue, Swiss Blue and London Blue Topaz varieties. The irradiation process involves exposing gemstones to electrons which alters its crystal structure. Therefore, it changes how the gemstone absorbs light frequencies.
Oiling treatment –
Emerald often undergoes oil treatment because they naturally have surface-reaching inclusions. In addition, oils, such as cedar oil, penetrates cracks and makes them far less noticeable. Most importantly, oil has a similar refractive index as gemstones, allowing less interference of light play. As a result, the clarity improves. Consequently , oiled stones need special care, so that the oil is not removed.