I see this a lot.
A guy wants to buy a diamond. He starts looking at diamonds, regular round brilliant diamonds, as that’s what is the shape the majority of diamonds are cut into.
After a while he notices that princess cut diamonds are a little cheaper than round brilliant diamonds by carat weight, all else being equal.
So he wonders if maybe a princess cut diamonds might be just the thing. After all why not get a little more bang for your buck?
Of course he has to start learning about diamonds all over again as the geometry of a princess cut diamond is different to a round brilliant. He discovers to his dismay that not all grading reports include the cut quality grade for princess cut diamonds.
So he finds himself looking for a jeweler that sells AGS graded princess cut diamonds. But it doesn’t seem as though these diamonds are any cheaper as they are much better cuts than the round brilliant ones he was looking at initially.
A little frustrated he goes back the the drawing board.
He begins comparing all the different shapes and notices that some are definitely cheaper than princess cut diamonds. Emerald cuts, and Asscher cut diamonds seem to be priced just below princess cuts, by carat weight, all else being equal. He then notices that oval cut diamonds are also cheaper than round brilliant diamonds, though not as cheap as the princess cuts he initially found.
It becomes quite complicated to find the best “bang per buck” because the way diamonds are priced is very very efficient. The industry is finely tuned to the demand for each shape.
The reason round brilliants remain the most expensive is because they can be cut and polished in such a way to provide the most impressive sparkle. But since diamonds in the rough are octahedral more of the rough is removed to cut round brilliants than is required for most other shapes. Simple as that. It’s geometry. It’s basic mathematics.
The best light performance is obtained by cutting a round brilliant. An oval cut diamond can’t be cut in a way to have better light performance than a round brilliant can be. It’s impossible. Sure you can have poorly cut round brilliants that look worse than a well cut oval. But if both stones are cut to the very best specifications the round brilliant will always look more “diamond-ey”. It returns light to the eye of the beholder in a concentrated way and that is something the geometry of other shapes simply won’t allow.
This makes round brilliant destined to be the best seller, hence this shape will see the greatest demand, and consequently the price will reflect this demand.
Mind you, demand is not the only factor. Some shapes are not cut very often as the natural way a rough diamond appears does not lend itself to be cut into some more peculiar shapes. Please don’t ask me to find you a shield cut diamond. So far I haven’t had any luck with that. Also the Marquise cut as shown in the chart below can be priced even higher than round brilliants.
So let’s look at the numbers from Blue Nile.
What’s the actual dollar difference between, say, a radiant cut diamond, oval cut diamond, round brilliant, and so on, with all other quality factors being equal.
Here we have 10 different shapes, or cuts, as they are called in diamond-speak. Each is the price of a 1 carat diamond and they were all selected to have 4 C characteristics as close as possible to each other.
The marquise cut ends up being the most expensive. This is likely because it requires the removal of more of the rough, so it’s not often chosen as the optimum shape when examining the rough.
At the time of writing Blue Nile lists 2,772 marquise cut diamonds.
Compare that to almost 4 times as many princess cut diamonds listed on the Blue Nile website.
The biggest savings are seen in the pear cut diamond with the cushion cut diamond, emerald cut, and Asscher following close behind. Princess cut is in 6th place if we rank them from highest to lowest.
The pear cut comes out as the cheapest cost per carat at present.
The price of diamonds is affected by both the demand and the amount of rough that is sacrificed during cutting.