A diamond is one of the best-known and most sought-after gemstones. Diamonds have been used as decorative items since ancient times.

A carat (ct.) is the unit of measurement specifically used to describe the weight of a diamond (or other gemstones). A single carat is equivalent to 0.2 grams, or 200 milligrams, and is divided into 100 points. Don't confuse "carat weight" with "karat," the method of determining the purity of gold. AA certified diamond that comes with a grading report, indicates the exact carat weight to the nearest hundredth of a carat, in decimal format. A 1-carat diamond has 100 points (1.00) while a ¾ carat stone has 75 points (0.75). Carat weight in pre-set jewelry is typically described as a fraction (e.g. ¾ carats) and has an equivalent decimal range (¾ carats = 0.69 – 0.82 points).

The table below correlates fractional sizes with their decimal equivalent:

Carat FractionDecimal Equivalent
1/10.09 – .11
1/8.12 – .13
1/7.14 – .15
1/6.16 – .17
1/5.18 – .22
¼.23 – .28
1/3.29 – .36
3/8.37 – .44
½.45 – .58
5/8.59 – .68
¾.69 – .82
7/8.83 – .94
1.0.95 – 1.05

Carat Weight and Price

Diamonds are mined from deep within the earth's crust. Rough diamonds are either too small or inferior in quality to produce glimmering and polished products. The rarity of larger, high-quality diamonds has resulted in significant price escalations between sizes. For example, a one-carat diamond can command four to six times more than a half-carat diamond.

Selecting a Carat Weight

  • Price of a Diamond is determined by its carat weight, and broken down in half-carat increments. Thus, assuming factors like cut and clarity are equal, a diamond weighing one carat will cost more than a diamond weighing slightly less than one carat.
  • While the diamonds carat measurement indicates the weight of a diamond, its length and width measurements indicate the actual physical size, or how big the diamond will appear when viewed from top. Diamonds can vary in size even though they are of the same carat weight. For example, a round diamond of one-carat could measure 5.9 mm in diameter, on the other hand a round diamond of one-carat could be 6.5 mm wide. Broader diamonds with larger millimeter measurements create greater visual impact.
  • The price of a diamond is affected by the carat weight, hence higher the carat weight, higher the price of the diamond.
  • Click here to see detail diamond sizes chart.
Asscher-cut, often described as a square Emerald. Even Asscher-cut diamonds have a pavilion thatis cut with rectangular facets in the same style as the Emerald Cut. Named after the renowned diamond cutter Joseph Asscher, introduced first in 1920. What sets it apart from the othershapes are its uniquely angled and cropped corners. The facets of a properly cut Asscher diamond is compared to a hallway lined with reflective mirrors, radiating a great deal of sagacity. Since the cutting style of an Asscher diamond makes imperfections more visible, its recommended to choose a clarity grade of SI1 or higher.
Emerald-cut diamonds with its long lean lines, gives it a timeless and elegant look. The rectangular cut with a relatively larger open table (top, flat surface) and fewer facets highlights the clarity of the diamond more than any other shape. The Pavilion is what makes this shape different, which is cut with rectangular facets to create to create a unique optical appearance. Distinguished by its bevelled corners and step facets, this type of diamonds is more transparent than other shapes. Emerald-cut diamonds can vary greatly in how rectangular they are. For a Classic Emerald-cut shape, look for a length-to-width ratio between 1.30 and 1.40. An Emerald-cut diamond that is marked by an inclusion will be much more likely to be detected with the naked eye. Hence while choosing an Emerald diamond, its recommended selecting a clarity level of SI1 or higher.
The fancy-shaped Heart diamond is for the confident woman who is all heart. While sometimes selected for engagement rings, it makes a beautiful choice for pendants in fancy colors such as yellow, pink or red. The unique look of the heart-shaped diamond helps make it a distinctive choice for a variety of diamond jewelry. This unique shape is similar to a pear-cut diamond, differentiated by two rounded edges and a cleft at the top. Most high-quality heart-shaped diamonds are cut with 58 facets, although there are some variants depending on the cutting technique used. For a more traditional heart-shaped diamond, look for length-to-width ratios between .90 and 1.10.
A Marquise shaped diamond with its brilliant cut and tapered point at two ends gives it a timeless elegant look. Reputed to have been made for King Louis XIV of France, who demanded for a diamond which simulated the smile of Marquise de Pompadour. Due to the extended length Marquise diamonds have more size per carat weight than other shapes and boast its 58 facets. These diamonds when worn as a ring creates an elongated, slender look and makes the finger appear longer. For most traditional Marquise-cut diamonds, look for length-to-width ratio between 1.75 and 2.25.
Cushion-cut has been popular for more than a century. Cut into a square or rectangular shape with rounded corners and sides, it's considered by many to be a softer version of the Emerald cut. With a soft and romantic look, the Cushion-cut has rounded corners and larger facets to increase the stone’s brilliance. For a cushion-cut diamond that is square, look for length-to-width ratios between 1 and 1.05. If you prefer a rectangular shape, look for length-to-width ratios greater than 1.15.
Oval-cut diamonds are timeless and classic, its elongated shape gives a flattering illusion of length to the fingers. The Oval diamond has beautiful brilliance that’s similar to a Round diamond. Cuts with the same number of facets as a Round-cut diamond, an Oval-cut diamond emits nearly the same level of brilliance and fire. Its elongated shape makes it appear larger in carat weight than a Round-cut diamond. An Oval-cut diamond can be 'Short and fat' or 'Long and thin' so one must check the length-to-width ratio of the diamond prior to the purchase. For most traditional Oval-cut diamonds, look for a length-to-width ratio between 1.33 and 1.66. However, some people prefer ‘Long and thinner cuts’ and some prefer ‘Rounder and softer cuts’.
Pear shaped diamond also known as "teardrop diamond" because of its shape. The pear shaped diamond is a combination cut of the Round-cut and the Marquise-cut diamond. The unique look of the pear shape helps make it a popular choice for a variety of diamond jewelry. There are some variations among pear-cut diamonds, with some appearing wider and others exhibiting a longer, narrower shape. Pear diamonds are noted for their slenderizing effect, creating the illusion of longer, and more tapered fingers. They are also renowned for their high levels of brilliance, boasting 58 radiant facets. To understand what the diamond will look like when viewing it from above, look for a length-to-width ratio between 1.45 and 1.75.
The second most popular diamond shape is the princess cut. The admirable brilliance and unique cuts make the Princess-cut diamonds favourite for engagement rings. Princess cut diamonds have 90 degree corners and is one of the most efficiently produced types of diamonds, with nearly 60% of the original rough preserved during the cutting process. Princess cut diamonds are square or slightly rectangular in shape with pointed corners and an array of intricate facets that increase the diamonds inherent shimmer. Princess cut diamonds can vary greatly in how square or rectangular they are. The dimension of the princess cut diamond can be understood by the length-to-width ratio, which will help in determining what the diamond will look like when viewing it from above. For a Princess diamond shape that is square, look for length-to-width ratios between 1 and 1.05, for a rectangular shape, look for length-to-width ratios greater than 1.10.
Trimmed corners are the signature of this diamond, which makes it popular and a versatile choice for jewelry. The unique shape is a stunning hybrid of a traditional Round-cut and an elegant Emerald-cut, resulting in a near-square or rectangular orientation. The intricate 70 facets of the Radiant-cut diamond brings out the most brilliant, fire and sparkle. Radiant-cut diamonds can vary in their degree of rectangularity. For a Radiant diamond shape that is square, look for length-to-width ratio’s between 1 and 1.05. For a rectangular shape, look for length-to-width ratio greater than 1.10.
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