The 4 C's of Gemstones - Cut, Clarity, Carat, Colour
The value of a diamond is determined by the combination of the 4 C's. Cut, Clarity, Carat and Colour can vary drastically, but the most important to issue of value is, can any variations be seen with the naked eye or with magnification of 10x. Nearly all diamonds have "inclusions" or small markings. These make each diamond totally unique and, in fact, diagrams are often made of a diamond's characteristics for identification purposes. Again, it is the combination of the 4 C's which determine the value, as a small inclusion may be cut away using an extra facet in the cut, or the colour of a diamond may influence whether or not an inclusion may be seen without magnification. Diamonds actually range in colour from colourless to yellow and brown. In addition, there are fancy diamonds such as yellow, pink, purple, blue, green, orange, black, etc. A truly colourless diamond is very rare. In fact, although diamond colour ranges from D (colourless) to Z (yellow/brown), most diamonds appear colourless to the naked eye until the M/N range. Again, the cut and setting can make the diamond colour appear lighter or darker. The size of the diamond greatly influences the price. Most diamonds used in jewellry are under 1 carat - the majority being approximately .25 carat or less. The price of individual diamonds jump dramatically at the sizes of .25 carat, .50 carat, and 1.0 carat. This is due to the increased rarity of the stones as they are larger, and the increased costs of manufacturing them to a quality which brings out the best in each stone.
In sum, there are innumerable variations in diamonds. While there are preconceived ideas of "flawless white" gem, these are rare. The main factor to take into consideration is - do you like it? Do you like the setting? Has the gem been fashioned and cut carefully by skilled diamond cutters? Are there flaws which can be seen with the naked eye, or do they affect the brilliance and fire of the stone? With regards to price, remember that the variations can be adjusted. 2 small diamonds will be less expensive than 1 large. By moving up or down a grade in colour or clarity, the price will change, but the diamond appears to be the same. In the end...it is a matter of taste and personal preference.
Cut
The cut of a diamond - its roundness, its depth and width, the uniformity of the facets - all determine a diamond's ability to refract brilliance. The Cut of the diamond is the only quality that is within man's control. Many Gemologists conider the cut the most important diamond characteristic, as even if a diamond has perfect colour and clarity, a poor cut will dull its brilliance.
The width and depth of the cut have the greatest effect on how light travels within the diamond, and how it exits in the form of brilliance. If the cut is too shallow, the light is lost out the sides causing the diamond to lose brilliance. If the cut is too deep the light escapes out the bottom causing the diamond to appear dark and dull.
For this reason, the cut is determined by the diamond's proportions, specifically the depth compared to the diameter. The diameter of the girdle (nearly the highest level) compared to the diameter of the diamond will determine how well light will reflect and refract within the diamond.
| Terms used in cuts ..... | |
|---|---|
| Diameter | The width of the diamond as measured through the girdle |
| Table | The largest facet of a gemstone |
| Crown | The top portion of a diamond extending from the girdle to the table |
| Girdle | The narrow band around the widest part of a diamond |
| Pavilion | The bottom part of a diamond, extending from the girdle to the culet |
| Culet | The facet at the tip of a gemstone. The preferred culet is not visible with the unaided eye (graded "medium" or "none") |
| Depth | The height of a gemstone measured from the culet to the table |
Colour (Specific to Diamonds)
A gem acts as a prism, dividing light into a spectrum of colours and reflecting this light as colourful flashes called "fire". The most important thing to know about colour is; The LESS colour a diamond has, the more valuable it is. For the purist, look for a colourless diamond with a grade of D- F and a fluorescence rating of none, faint, or slight. For an excellent value in a diamond with no noticeable colour to the unaided eye, look for a near- colourless grade of G-I, and a fluorescence grade of medium or strong blue. Or, if you'd rather not compromise on colour but would like to stay on budget, choose a diamond with a good cut and SI1–SI2 clarity and consider going with a strong fluorescence. It will still be beautiful to the unaided eye and you may prefer the unique effect of a strong fluorescence.
Flourescence is a glow, usually of a bluish colour, that emanates from some diamonds is when it is exposed to ultraviolet light. Strong fluorescence is not desirable, but faint fluorescence does not affect the appearance of a diamond. The most common source of UV is a black light. When exposed to UV light, many diamonds will give off a distinctive glowing blue colouration.Although fluorescence may be displayed in various colours, blue is the most common in diamonds. The fluorescence of a diamond is defined by its intensity as either None, Faint, Medium, Strong, or Very Strong. Although fluorescence is a characteristic that can be measured, it is seldom an issue when selecting a diamond.
| The Colour Codes | |
|---|---|
| D: Absolutely colourless | 100% clear diamond colour grade,which is very rare. |
| E: Extremely colourless | A trained gemologist can detect slight colour. A high-quality diamond |
| F: Colourless | Only trained gemologists can detect colour. Lowest of the colourless grades |
| G-H: Near colourless | When compared next to better colour grades, a slight colour is detectable but only by trained gemologists and only out of a setting. It is a much better value |
| I-J: Near colourless | Colour in I only detectable out of setting |
| J, K, L | Colour slightly detectable, but in stones under .50 carat appear colourless to untrained eye. An excellent value. |
| K-M | Colour is visible.The colour is more obvious in larger stones and when set in white metal |
| N-Z | The lowest quality of diamonds, the colouration is clearly visible, even in small diamonds |
Carat
A diamond's weight is measured in Carats, a small unit of measurement equal to 200 milligrams or 0.2 grams. (Don't confuse this Carat with the term Karat, which is a measure of the purity of gold). One carat is divided into 100 points. A diamond weighing one quarter of a carat can also be described as weighing 25 points or 0.25 carats. Note: A 2-carat diamond does not appear to be twice the size of a 1-carat diamond when viewed from the top.When diamonds are mined, large gems are discovered much less frequently than small ones, which makes large diamonds much more valuable. In fact, diamond prices rise exponentially with carat weight. So, a 2-carat diamond of a given quality is always worth more than two 1-carat diamonds of the same quality.
What is the best size to purchase? To choose the best carat weight of diamond, consider the style, the size of her finger, the size of your setting, and your budget. If you have a set budget, explore all your options and you'll find that there is a wide range of diamond carat weights and qualities available in your price range. Consider a smaller size diamond or a setting that protects a larger diamond from getting knocked against doors and counters. Also keep in mind that the smaller the finger, the larger the diamond will appear. A 1½-carat diamond solitaire looks much larger on a size 4 finger than a size 8 finger. If you have already chosen a setting, to make sure you choose a diamond to fit, look for the diamond size specifications of your ring. Finally, if a large carat weight is important to you, yet you're working within a budget, consider a diamond with a good cut, SI1-SI2 clarity, and an I of J color grade.
Clarity
Almost all diamonds and most gems contain very tiny natural birthmarks known as inclusions. To determine a diamond's clarity, an expert views it under 10-power magnification. In addition to internal inclusions, surface irregularities are referred to as blemishes. These two categories of imperfections- inclusions (internal) and blemishes (external)-make up clarity.The fewer the imperfections, the rarer and more valuable the diamond. Many inclusions are not discernable to the naked eye and require magnification to become apparent. A laboratory-certified clarity rating of SI2 represents the point at which inclusions are technically not apparent to the average naked eye. What is the best Clarity Grade? It is recommend that you select an "eye-clean" diamond - one that has no inclusions visible to the unaided eye. An excellent value, diamonds of this clarity are much less expensive than IF- or FL-grade diamonds and typically do not contain visible inclusions that detract from the beauty of the diamond.If you're considering an SI2 grade diamond, speak to the vendor and ensure that the inclusions are not visible with the unaided eye. But, if you'd rather not compromise on clarity yet are budget conscious, choose a diamond with a good cut and G or H colour.
| Diamond Clarity Grades | |
|---|---|
| FL, IF | Flawless has no internal or external flaws, and internally flawless has no internal flaws. Very rare and beautiful diamonds |
| WS1, WS2 | Diamonds:Very, very slightly included. Very difficult to see inclusions under 10x magnification. An excellent quality diamond |
| VS1, VS2 | Very slightly included. Unable to see inclusions with an unaided eye. Less expensive than the VVS1 or VVS2 grades |
| SI1, SI2 | Slightly included. Inclusions are visible under 10x magnification. In SI2 diamonds, inclusions may be visible with the unaided eye. A good diamond value |
| I1, I2, I3 | Included. Contains inclusions that may affect transparency and brilliance.Possibly large included crystals |
