Colour - The 4 Cs of Gemstones

four c's of gemstones


A colourful gem's appearance results from several different variables, each of which is interconnected and influenced by the others. The intricacy of these interwoven interactions has thwarted all attempts to measure quality. Even yet, every time a dealer buys a gemstone, they do a brief mental examination, which generally takes only a few seconds.

The "4 C's" of gemstones: carat, colour, clarity, and cut, are used to determine the value of a gemstone. For the buyer, knowing all four of these is essential background information. If you're buying a valuable stone for four figures or more, buy it loose so you can see it weighed and study it thoroughly. Understanding the four c’s of gemstones can help you comprehend them in a better way.

Rubies and emeralds, for example, have distinct colours and saturations that are highly appreciated and sought for. The kind or amount of clear qualities in a jewel can increase or reduce its appeal, and the shape of a gemstone can also influence its beauty.

The four C’s of gemstones

  1. Carat is a unit of measurement used in the gemstone industry to quantify size. One metric carat is equal to 200 milligrammes, or one-fifth of a gramme. Jewels are sometimes measured in tenths of a carat, or 0.01 carats. Jewels of two distinct species with the same cut and size may have various chemical formulas, elements, and densities due to the various chemical formulas, elements, and densities that make up different carat weights. While certain gemstones, such as topaz, are accessible in a wide variety of carat sizes, others, such as tsavorite garnets bigger than five carats, are less frequent. Massive rough is possible because of the environment in which some gemstones originate, such as pegmatites. In some instances, the heat and pressure that generates natural gems only allow for the formation of smaller stones. Less common big stones have a higher price per carat because of their rarity. A one-carat stone is more precious than its half-carat relative when all other conditions are equal. Colours that appear better in higher carats are preferred in some jewels. Larger crystals may have more vivid colours, especially when it comes to stones like kunzite or aquamarine, which have more pastel tones.
  2. Cut- Gemstones in their natural condition have a wide range of shapes and colours. Alluvial stones, discovered far from their source, can have frosted glass-like colours and crumbled pebble-like shapes. Other surfaces may have a well-defined habit that indicates their underlying atomic structure, such as columns, pyramids, and star forms, among other things. These stones may not be the same hue all the way through, but they have a range of shades. Jewels are cut to bring forth the maximum amount of attractiveness. A translucent stone was brightened by a skilled gemstone cutter, with light bouncing off its surface and from within the crystal. The colour of the gem is maximised, with consistent colours when viewed from above and tone and saturation that are as near to perfect as possible. Its rough form generally influences the contour of the faceted stone. Tourmalines are frequently cut into baguettes, emerald cuts, and other elongated forms because they develop as thin columns. Flattened rough, like corundum samples, can be faceted into gems with wide tops and bottoms. Colour zoning is another aspect that influences the cut. If a gemstone is prized for its pure blue hue and the rough has blue and blue-green sections, the cutter will strive to place the final jewel such that as much of the desired colour as possible is present.
  3. Clarity- The presence of evidence of their origin, such as minute gas bubbles or repaired fissures, influences the look of most gemstones. Some gems are made entirely of crystal, giving the spectator a clear glimpse of the stone. Other gems have specks here and there that can influence the transparency of the diamond or the flow of light through it. The peculiarities on and within gemstones are known as clarity characteristics, and this notion is referred to as clarity. Imperfections and inclusions are the two types of blemishes that may be seen in clarity. The former are scratch or polish lines that appear on the surface of a gemstone. Foreign crystals, pockets of fluid, or partly healed fractus are examples of inclusions found inside the gem. Coloured gemstones are held to different criteria than diamonds when it comes to clarity. Coloured gemstones have three types of clarity.  Type I gemstones are eye clean, meaning no clarity features can be seen with the naked eye. This style of jewellery is in high demand. Inclusions are evident in Type II gemstones, but they do not affect their durability or aesthetic appeal. Type III gems have a wide range of clarity qualities, typically the product of the environment in which they grew or the conditions in which they were mined.
  4. Colour- Color is one of the first characteristics that one sees while gazing at a gemstone, and it is this quality makes gemstones so appealing. Rubies are known for their red hue, emeralds for green tint, and opals for their colourful flashes. However, the hue changes a lot. Colour differences can occur even among diamonds of the same species, with the same trace components and excavated in the same area. The term "body colour" relates to whether a jewel is red, green, or another hue, as well as the stone's bright or dark hue and intensity. The chemical formula of the stone, the presence of any trace elements, and how the gem is cut are all variables that impact the body colour of a gemstone. Some diamonds have extra colours in addition to their body colour and are classified accordingly. Most gemstones are known for having a particular colour or colours that are particularly attractive. Pure blue sapphires and pure green to bluish green emeralds are two well-known examples. This is the "fine colour" of a gem. Fine colour in a gemstone is in more demand than other accessible colours and hence has a higher value. The “colour range” of a gemstone refers to the many hues found in it. The colour spectrum can be limited, as in peridot's golden greens, or broad, as in sapphire and tourmaline. While some colours in a colour range may be more popular than others, many designers like creating jewellery that spans the whole spectrum, such as sapphire suites in blue, yellow, and pink.
  • Many elements, including light, influence the colour of a gemstone. White light, unlike pigment, is made up of every colour in the visible spectrum. Colour appears in a gem when white light reaches the stone at its most fundamental level. The red in rubies, the green in emeralds, and the colours of other jewels are created by the absorption of some colours while the eye reflects others.
  • The precise colour of a gem is determined by its chemical formula, trace components, cut, and other factors. Trace elements are non-chemical elements that fill in the gaps in the crystal structure of a stone. One or two of a thousand molecules in a stone made up of a-b-c-d, for example, might be a-b-x-d. These minor variations are sufficient to alter the hue of a stone.
  • Although beryl gems such as aquamarine, morganite, and emerald are all beryl, the presence of iron, manganese, chromium, or vanadium in the crystal structure alters the colour and identification the gem. Colour is an inherent component of the design of some diamonds, rather than being influenced by external causes. The iron in peridot and almandine garnet's chemical formulae gives them their colours.
  • The spectrum of possible colours in these gems is limited than in other stones. Therefore there may be variations in tone or saturation. Such a gem may be accessible in shades ranging from faintly yellow-green to yellow-green; however, pure yellow or green may be out of the question. Colour centres, small flaws in a jewel's atomic structure that allow the real gem to interact with light differently, generating colour, impact even more stones.
  • Gemstones with colour cores must be subjected to radiation to reveal their true brilliance, either naturally or artificially. Radiation interacts with the subatomic particles of a stone, causing a delicate action that results in colour.
  • Some gemstones have many colours. As in the case of tourmaline and ametrine, this might appear as colour zoning. In other cases, the components inside the crystal structure lead the stone to interact with light uniquely. When exposed to sunlight, these jewels will reflect one colour, such as purple, while when exposed to incandescent light, they will reflect a different colour, such as blue.
  • Colour change is the term for this visual phenomenon. Alexandrite is the most well-known and famous colour changing gemstone. Traces of chromium react with light and the gem's chemical composition in this gemstone, allowing it to absorb both red and green light. When exposed to light containing a lot of red, such as sunshine, the balance is tipped, and alexandrite appears red.
  • The gem becomes green when exposed to blue or green light. Spinel, sapphire, and garnet are examples of gemstones that change colour. Their phenomenon, like that of alexandrite, is produced by trace elements. However, the particular element varies depending on the gemstone kind. Different hues, such as blue and purple instead of green and red, maybe emitted.
  • The number of colours in different white lighting has an impact on colour change gems. These gemstones are relatively rare as a whole, with those that shift into vivid colours, in particular, being sought after.
  • The trace elements, colour centres, and other variables that define the colour of a gem aren't usually equally distributed throughout the crystal. The hue of the stone might change depending on the conditions under which it was created. Patches of deeper saturation, lighter tones, or various colours throughout the raw diamond are possible.
  • Colour zoning is the term for this characteristic. Gem cutters strive to shape stones that exhibit the most of a particular colour in gems when a uniform hue is required. The cutter will attempt to produce a final stone with more vivid colouration if saturated colours are desired. If a client requests moderately toned stones, the cutter will do his best to shape them.
  • Colour zoning is minimised as much as possible in the finished gem by the cutters. Colour zoning is part of the attraction of gemstones like tourmaline and ametrine. In these cases, gem cutters attempt to position the final gems such that the hue contrast is visible. Cuts that are half one colour and half another are popular, as are bands of different colours running the length of the stone-like stripes.
  • It might be difficult to describe the hue of a gemstone. It's possible that simply describing a diamond as "blue" is insufficient to explain its look. Modifiers such as "sky blue" or "ocean blue" may evoke various mental pictures in different persons, resulting in an inaccurate impression of the stone.
  • Although terms like "Kashmir" or "Ceylon" blue may lend romanticism to the diamond, there are limitations against using a location as a description unless the stone originated from that region. The Gemological Institute of America (GIA) has developed words and ideas to aid in creating a standardised manner of defining colour. The colour of a jewel is assessed by GIA using hue, tone, and saturation principles. "hue" refers to the first impression one receives while looking at a diamond, such as red or yellow.
  • The term "tone" describes how bright or dark a gemstone is. Jewels with medium tones are in more demand than those with very light or dark tones. The intensity of a gemstone's colour is measured in "saturation." Low saturation stones might appear grey or brown-tinted, but high saturation gems can appear dark or bright, depending on the stone.


Nature has provided us with a wide variety of jewels, each with its distinct characteristics. To determine a gemstone's actual value, several elements must be evaluated. However, these stones are produced by a variety of laboratories, each with its grading system. Furthermore, each individual has a distinct taste. Therefore, when choosing a gemstone for a piece of jewellery, one should choose the stone that speaks to them.