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Choosing your Diamond

Choosing Your Diamond

Carat is the unit used to measure the weight of a diamond. 1 carat is equal to 100 points (0.5 carat is 50 points), and is equivalent to 0.2 grams. Round diamonds are commonly 0.3, 0.5 or 1 carat in weight. Then does a 60-point diamond look twice as big as a 30-point diamond, or is the table of a 2-carat diamond twice as big as that of a 1-carat diamond? The answer is no. As diamonds are 3-dimensional, as weight increases, the diameter of a diamond does not increase by the same ratio. Weight is only one factor that contributes to the value of a diamond, and does not alone determine its price. Other factors such as cut, clarity and colour are taken into consideration.

Before buying a diamond, it is important to set your budget. Here are some tips for choosing your diamond:

  • When making a decision, most customers use the reference point of investing one to two months’ salary into buying the diamond she deserves.
  • If a 1-carat diamond is out of your budget range, lower your expectations in colour, clarity or cut, and you will still be able to find a diamond that suits her.
  • Pay attention to your other half’s finger shape. If a 1-carat diamond does not suit the shape of her hand, consider stones under 1 carat.
  • Diamonds of the same size can look different when mounted on different rings. Consider the accessory as a whole when choosing the perfect ring for her.
  • Large diamonds are more rare than small diamonds, and the rarer the diamond, the more it is worth. Therefore, the price of a 2-carat diamond is not twice that of a 1-carat diamond.
  • Small loose stones (0.08-carat or under) are much cheaper by the carat, however, the cost of mounting these stones is higher. Therefore, finished products using small loose stones are not cheaper than those using a single stone of the same total carat weight.
  • Are diamonds the bigger the better? If the table of a diamond is disproportionately wider than its pavilion, the proportions of the entire diamond will negatively affect the reflection of internal light, which leads to reduced brightness and weak fire. Therefore, when choosing a diamond, a good cut is as important as carat weight.


Different grades of clarity can only be identified under 10-power (10X) magnification. Imperfections on the surface of a diamond are called blemishes, whilst internal irregularities are known as inclusions. The quantity, positioning, size and distinctiveness of these imperfections are criteria by which grades of clarity are defined.

Step 1: Consider the whole face of the diamond.

Step 2: Divide the face into four parts, and consider the upper, lower, left and right quarters in turn.

Step 3: Carefully consider each facet - the crown, pavilion and girdle.

Step 4: Finally, revisit the previous steps and re-consider your first impression of the diamond’s clarity.

Step 5: Determine the clarity grade of the diamond.

Diamonds are minerals that form underground, therefore a finished diamond still has the blemishes and inclusions it naturally contains from before it was mined. Gem-quality diamonds make up less than 10% of all stones mined. Diamonds of the grade VS and above are very rare, therefore one can imagine that there are no two stones that are identical to one another. Each diamond’s unique blemishes and inclusions are a good way of identifying individual stones, and provide a fair and professional standard by which a diamond’s clarity grade is judged.

Colourless diamonds are graded on the Gemological Institute of America’s D-to-Z scale, which ranges from DEFGHIJ to XYZ. D, E and F grades are the most sought after, however, the truth of the matter is that completely colourless diamonds are extremely rare. G to J grades are more realistically attainable for most customers, and only skilled graders can actually tell the difference between the top colour grades in finished and mounted diamonds. For example, F and G grades look very similar to the unaided eye, yet the price differs significantly. The best approach is to be pragmatic towards picking the colour grade that suits your preferences in both style and price.

If a diamond is to be graded accurately, it must be compared to a masterstone, which should fulfil the following criteria:

  • A master stone should be round and brilliant, and preferably emits no fluorescence when exposed to ultraviolet radiation.
  • It should be between 0.3 to 0.4 carat in weight.
  • It should be of Good cut or above, and of clarity grade SI1 or above.
  • 3 to 5 master stones of a range of known colours should be used in the grading process.

If a diamond is to be graded accurately, it must be compared to a masterstone, which should fulfil the following criteria:

  • Diamonds need to be graded under diamondlite.
  • The more yellow tint a diamond contains, the more obvious its colour will be.
  • Diamonds must be examined against a pure white background.
  • A well-mounted diamond can display its colour from multiple angles.
  • Graders must be focused on the task.
  • It is not uncommon for two people’s judgment of a diamond to differ by one colour grade.

A perfectly cut diamond should concentrate all light that enters the stone, and reflect brightness and fire from the table and crown facets. If the pavilion is cut too deep, light will not be able to refract internally and will be lost; if the pavilion is cut too shallow, light is leaked through the bottom once it enters. In both cases, the brilliance of the diamond is not truly reflected. If you look into the face of a diamond cut too shallow, you will see a fish-eye effect, while you will see a nailhead effect when looking into a diamond cut too deep.

It should be noted that a diamond’s outer shape is not a factor used to determine the quality of cut. Before a craftsman begins to cut a stone, he analyses the stone and decides the best way to cut it in order to retain the most carat weight but at the same time maximises its brilliance - this is known as fancy shapes. The most common shape in the market is round brilliants.


Some common cuts include Heart, Emerald, Marquise, Pear and Princess.

The best cut shows off a diamond’s brightness and fire. A diamond’s brilliance is mostly produced by the crown facets, and an Ideal Cut best showcases the skill of the craftsman and beauty of the stone.


The cut is the only factor contributing to a diamond’s beauty that can be controlled by the craftsman. The size, proportion, symmetry and polish of the cut, in addition to the different angles of the cut, give the diamond brilliance, dispersion and scintillation. The Ideal Cut brings out these three qualities in a diamond.

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