Diamond Cut Part 2: Crown and Pavilion Angles
In part one of this series we discussed how the Table and Depth Percentage effect the cut of a diamond.
In part of two, we'll take a look at the last two important factors of cut, the crown and pavilion angles, to give you a better idea of what you should be looking for when you purchase a diamond.
The relationship between the crown angle and the pavilion angle has the greatest effect on the appearance of any diamond. A slightly steep pavilion angle can be complemented by a shallower crown angle, and vice versa.
Diamond Cut Part 1: Table and Depth Percentage
Different aspects of a diamond
The cut of a diamond determines how well the stone reflects light. This reflection is responsible for the gem’s brilliance or overall sparkle. There are many aspects to a stone which contribute to angles and the cut form, as the diagram to the left indicates.
Diameter: The width of the diamond through the girdle.
Table: The largest facet at the top.
Crown: The Top part from the girdle to the table.
Girdle: The narrow band around the widest part.
Pavilion: The bottom part from the girdle to the cutlet.
Culet: The facet at the bottom tip. The preferred cutlet is not visible to the naked eye.
Depth: The height from the cutlet to the table.
Professional and skilled cutters cut the stone to mathematically precise proportions to allow as much light as possible to reflect from each of its mirror-like facets out of the top of the diamond.
Choosing a Diamond: Size v.s Quality
The term ‘rock’ is commonly used to describe a diamond of a significant size, and so along with this our intrigue over big stones has grown. Its a popular word when describing celebrity engagement rings, as their status goes hand in hand with the size of the diamond they present for their loved one. Its all very well drooling over the latest big diamond in the celebrity world, but in the real world, does size really matter?
Size and Quality
Most have a realistic budget that they work towards when they are looking to purchase a diamond, and so ‘rocks’ for the majority of people are not always practical. It is also important to remember, however, that the value of a diamond is based on the well-known ‘4 C’s’, which includes the specifics of the quality of the diamond and indeed the size as well. Furthermore, diamonds of a large carat size may not be practical for everybody during day-to-day wear, or they may just not suit your taste, and so in this option the quality is the main focus in your search.
What are the differences between diamond grading labs?
Consumers need to be aware that there are variations between different diamond labs when making a diamond purchase. Although many reputable jewellers offer uncertified diamonds with their own brand name or appraisal included, ideally a diamond should come with a grading report from a well known and reputable lab.
Most diamonds sold come with a diamond certificate or grading report which authenticate a diamond’s attributes. These reports will include features such as cut, shape, carat, colour, clarity, dimensions, etc.
There are many different diamond grading laboratories, but no across the board standards so different labs can produce different reports for the same stone.
Several renowned grading agencies in the United States and Europe have high reputations and different levels of standards:
- Gemological Institute of America (GIA): The foremost authority on diamonds. They set the standard for accuracy in grading diamonds particularly based on colour and clarity. Labs from all over the world commonly use GIA master set stones to compare colours and clarity grades when they're uncertain on a grading.
What are ideal diamond proportions?
Single example of Tolkowsky’s Theorem's predicted proportions.
Proportions determine a diamond's brilliance (the amount of light reflected back to your eye), fire (the flashes of colour due to prismatic separation into the colours of the rainbow) and scintillation (sparkling movement of light as you move the diamond). If ideal proportions are used in the creation of diamonds, their overall excellence can be optimised.
In 1919 Marcel Tolkowsky was responsible for discovering the basis of what is now regarded as the “Ideal Cut” diamond. The Mathematician formed a Masters thesis on the proportions for round brilliant cut diamonds.
Supposedly, he conducted his research by asking Londoners to select the most appealing diamond from a small group. He combined these observations with those of his family’s Belgian diamond cutter business and then applied maths and physics to confirm why certain proportions produced the best looking diamonds.
The image shows a single example; in fact Tolkowsky’s theorem predicted a range of proportions with varying combinations of pavilion and crown angles that could enhance brilliance and fire. A variation on this was the Eulitz cut, developed in 1972 and considered to be ‘mathematically perfect’.
10 Steps to Choosing the Perfect Engagement Ring
Deciding on the perfect engagement ring to give to your intended is extremely challenging if you don’t know where to start. Here is a 10 step simple guide to choosing the right ring for her.
Before you start looking at jewellers
- 1) DECIDE ON A BUDGET AND KNOW HER SIZE
Your personal budget must be considered when purchasing a ring and it is better to do so before you start shopping around. It is conventionally suggested that you spend at least two months worth of your salary on a diamond engagement ring. Ring prices can begin modest, but can range quite high so you’ll need to weigh out your wallet size with her preferences. You should also make sure that at this point you have a measurement for the ring size. Read here if you want tips on finding it without her knowing!
What Makes a Diamond Sparkle?
Diamonds are notoriously known for their sparkle and shine, but in the rough this is not the case. The crystallised carbon has to go through several processes in order for it to look like the finished product. Included in these processes is the cutting and polishing of the diamond, which are the main factors determining the sparkle and lustre of the diamond.
Diamond Cut
Being one of the four C’s the diamond cut is signalled as an important factor when choosing a diamond ordinarily. The cut is frequently classed as the most important characteristic of a diamond, and has the greatest influence on the diamonds beauty and appearance. Therefore, it is also the greatest determinate in the general sparkle of the stone. The cut refers to the overall polish of the diamond from rough and is a measurement of the amount of light able to travel through the diamond. GIA rates the cut of diamonds on a scale from Excellent, Very Good, Good, Fair to Poor.
10 Things To Know Before Buying a Diamond: Part One
Purchasing a diamond can seem quite daunting when confronted with all the terminology and specifications used in making a selection. However, you don’t need to be a diamond expert to make a confident and knowledgeable decision. In this article we will guide you through the 10 most important factors that you need to know in order to get the best diamond for your money. Part two will follow, here are the first five...
1. Carat Weight
Although it might seem the bigger the diamond the better, to get the best value for your money you’ll need to find a good balance between quality and size. Carat, one of the 4 C’s, is the unit of diamond weight. One carat is equal to 0.2 grams.
The carat weight will give you an idea of the size of your diamond, however twice the weight does not mean twice the size. This also works as a roundabout correlation for other diamond shapes. To get a better sense of how carat weight relates to diamond size take a look at our diamond sizing chart.
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