There are many measurements that go into creating a diamond that truly maximize the refraction of light. Facets must be cut at exactly the right angles relative to one another; the top and bottom halves of the stone must have the proper depth relative to each other; the table, or flat surface on the top, must be the correct size, relative to the overall size of the stone. And, of course, the facets on the top (crown) and bottom (pavilion) must align correctly with each other. An 'ideal cut' is a specific set of guidelines that delineate the proportions and measurements that give a diamond the highest amount of fire and brilliance.
These measurements and percentages are different for each diamond, and are all taken into account in the evaluation of a diamond's cut. In fact, each diamond shape (heart, round, oval, emerald, etc.) has its own set of guidelines for what makes an ideal, excellent, very good, good, fair or poor cut.
The first step in choosing a diamond is deciding what shape you like. While the round shape is the most popular, there's plenty of other beautiful shapes to choose from which deliver brilliance and fire. Of course, the most popular and commonly seen shape for diamonds is the round or brilliant cut, which has 57 or 58 facets (depending on whether the cutlet, or point at the bottom of the stone, is faceted or not). It's the 'classic' shape that most people think of when they think of a diamond. But the round cut is by far not your only choice. All shapes are capable of fantastic fire and brilliance. The only difference is the result of the diamond cutter's decision to cut the rough diamond into that particular shape.
The most important factor in determining shape, of course, is what appeals to you, and what looks best on your hand. Longer and shorter stones can visually affect the appearance of your hands, making them look longer or shorter in return. Also, your taste may guide you toward more traditional shapes, like the classic round brilliant, or toward less conventional shapes like pear, marquise or heart. While the shape of the diamond you choose is ultimately a matter of personal preference, there are differences in the various shapes that affect their brilliance, apparent size and value:
- Round brilliant-cut diamonds show the most brilliance and sparkle of all the shapes. When it comes to hiding imperfections, the round brilliant cut is the king. Its design allows it to hide flaws and yellow tints better than diamonds of other shapes. In emerald cuts and baguettes, which have long, flat facets, flaws become the most obvious.
- Emerald cuts, while sleek and attractive, are not quite as brilliant. If you like the square or rectangular shapes of an emerald cut, you may want to consider a radiant, princess or quadrillion, which have more facets and therefore more brilliance.
- If you want a diamond that looks as big as possible, even if it doesn't weigh much, consider a fancy shape like a marquise or pear, which appear bigger and longer than round diamonds of the same carat weight.