The name diamond shape is self-explanatory. It is addressing the shape in which the rough stone is fashioned. Diamond cut on the other hand, is a term concerning the proportions and quality of finish and it is addressed in another article. The diamond shape is of interest to the potential engagement ring buyer for two reasons. The first one is associated to aesthetic preferences – the second to the price.
In the diamond industry the shapes are classified in two major groups – round and all the rest jointly referred to as fancy cuts. The “round” is short for modern round brilliant cut with 57 facets. Older round shape cuts like “rose” or “old mine” are in extremely low demand and are not worth discussing for the purpose of this article. I am not familiar with the official statistics but by my records rounds amount for about 90% of the diamonds set in engagement rings. The fancies by order of popularity are: princess, cushion, radiant, marquise, pear, emerald and heart. The supply follow the demand and if your choice is a fancy shape towards the end of the list, expect limited availability.
The rounds are about 30+% more expensive then the same quality fancies, mainly due to the much higher demand. The only fancy diamond shape that sells for the price of a round one is the marquise. At least this is how it is priced in South Africa. There should be a reason for this but so far it remains secret, at least for me. 30% is a huge difference in price and one would expect it to balance the demand on the market. It does not and there are various reasons for the round brilliant diamond shape’s market dominance. Besides the flexibility of the round shape when it is integrated in any design, this shape has well classified cut (proportion) standards, assuring the best possible reflective factor. In other words it has more sparkle.
There is another reason which dampers the benefits of the lower price for fancies. The round shape simply looks bigger. What we see on the engagement ring is the spread of the stone and not its weight (carat). When we pay however, the price is per carat. If we compare for example a 1ct round shaped diamond with its closest market rival the princess (square) cut also 1ct and the same quality, we will perceive the round stone as much bigger. In order to visually perceive the two stones as equal in size, the princess has to be about 1.3ct. This is how the advantage of lower price for fancies disappears. When we consider the much better availability the scale is already leaning steady towards the round diamond shape.