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All else being equal, what causes diamond prices to vary so much by shape?

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AllAboardTheBlingTrain

Ideal_Rock
Joined
Apr 22, 2020
Messages
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I was messing around with stonealgo for my own amusement and discovered that diamond prices vary significantly by shape. I knew it had some impact of course, but I never realised how much. It got me thinking about why and I thought I’d pose the question here for the community!

Here are the (pre-tax) prices by stonealgo for every shape. I kept the following parameters (wherever relevant) constant: Triple Ex, None Fluoro, 1ct G VS2.

  • round: $6746
  • Cushion: $3362
  • Emerald: $4333
  • Oval: $4662
  • Princess: $4272
  • Pear: $5121
  • Radiant: $4065
  • Marquise: $6394
  • Asscher: $4106
  • Heart: $4248

Rounds are the most expensive, but followed very closely by marquise; while cushions are a bargain at half the price of a round per carat!

Is it wastage, ie cushions utilise most of the rough so the yield is higher from a piece of rough and therefore it can be priced lower (less rough needed to make a 1ct cushion)?

Is it popularity, ie vendors charge super high prices for marquise because they aren’t as popular and therefore sit around as dead stock for longer? Or the reverse - they charge higher for rounds because they are the most in demand and so people will pay?

Thoughts?
 
AllAboardTheBlingTrain said:
I was messing around with stonealgo for my own amusement and discovered that diamond prices vary significantly by shape. I knew it had some impact of course, but I never realised how much. It got me thinking about why and I thought I’d pose the question here for the community!

Here are the (pre-tax) prices by stonealgo for every shape. I kept the following parameters (wherever relevant) constant: Triple Ex, None Fluoro, 1ct G VS2.

  • round: $6746
  • Cushion: $3362
  • Emerald: $4333
  • Oval: $4662
  • Princess: $4272
  • Pear: $5121
  • Radiant: $4065
  • Marquise: $6394
  • Asscher: $4106
  • Heart: $4248

Rounds are the most expensive, but followed very closely by marquise; while cushions are a bargain at half the price of a round per carat!

Is it wastage, ie cushions utilise most of the rough so the yield is higher from a piece of rough and therefore it can be priced lower (less rough needed to make a 1ct cushion)?

Is it popularity, ie vendors charge super high prices for marquise because they aren’t as popular and therefore sit around as dead stock for longer? Or the reverse - they charge higher for rounds because they are the most in demand and so people will pay?

Thoughts?
Click to expand...

I am not an expert, but I think you pinpointed some of the reasons in your post.

Creating facets for different shapes surely includes varying levels of labor-intensive work and--I would guess--more labor and skill yields a higher price.

But, the cost difference between the round and the cushion is just wild!
 
Bijouteried said:
I am not an expert, but I think you pinpointed some of the reasons in your post.

Creating facets for different shapes surely includes varying levels of labor-intensive work and--I would guess--more labor and skill yields a higher price.

But, the cost difference between the round and the cushion is just wild!
Click to expand...

Both the cost difference between rounds and cushions; and the super high price of marquises shocked me!

I always thought that marquises weren’t a very popular cut so they would likely be priced cheap, but that they’re nearly equivalent to a round shocked me.

Also, cushions are the second most popular cuts after rounds, so I guess “popularity” doesn’t drive price at least in the “charge more for more popular shapes” way.

Going to suggest buying a cushion the next time I have a friend buying a ring where the recipient is agnostic to shape - you really can get more diamond for the same price (according to stonealgo, a 1.3ct cushion is about the same price as a 1ct round; all other parameters remaining equal).
 
The price for Marquise surprises me too, good job I am not a fan of that cut!

Fancy shapes are less popular for the general public based on my own experience.

In UK, I seldom come across fancy shapes or round stones that are not MRBs except at high end jewellery stores.

I prefer, in descending order for right hand rings: ECs, OECs and hearts, with the box for a heart cut stone still to be ticked.

DK :))
 
I think one big factor is how much rough has to be polished away and send down the drain to get the round shape, even though (to save rough) two rounds (with tables hugging) are often cut from one piece of rough.
I haven't seen many rough diamonds close to the shape of a round one.

Demand for rounds is highest, so they can get away with charging more for them.
 
AllAboardTheBlingTrain said:
Both the cost difference between rounds and cushions; and the super high price of marquises shocked me!

I always thought that marquises weren’t a very popular cut so they would likely be priced cheap, but that they’re nearly equivalent to a round shocked me.

Also, cushions are the second most popular cuts after rounds, so I guess “popularity” doesn’t drive price at least in the “charge more for more popular shapes” way.

Going to suggest buying a cushion the next time I have a friend buying a ring where the recipient is agnostic to shape - you really can get more diamond for the same price (according to stonealgo, a 1.3ct cushion is about the same price as a 1ct round; all other parameters remaining equal).
Click to expand...

I must admit that I am partial to cushions…. my three-stone with a cushion center and round sides was on my finger well before Prince Harry presented his! :twisted2:
 
It's said that it is entirely dependent on make. Waste ratios. Rounds waste the most material and so on.
Though, I actually do think there's a small bit of fluctuation based upon what shape is currently popular as well added on the back end for retailers selling the finished products. It would make sense.
 
dk168 said:
The price for Marquise surprises me too, good job I am not a fan of that cut!

Fancy shapes are less popular for the general public based on my own experience.

In UK, I seldom come across fancy shapes or round stones that are not MRBs except at high end jewellery stores.

I prefer, in descending order for right hand rings: ECs, OECs and hearts, with the box for a heart cut stone still to be ticked.

DK :))
Click to expand...

I think rounds are by far the most popular, followed by cushions I believe. My own personal favourites are ECs, but I also like OECs, pears and of course wouldn’t turn down an MRB though I wouldn’t call them my favourite!

kenny said:
I think one big factor is how much rough has to be polished away and send down the drain to get the round shape, even though (to save rough) two rounds (with tables hugging) are often cut from one piece of rough.
I haven't seen many rough diamonds close to the shape of a round one.

Demand for rounds is highest, so they can get away with charging more for them.
Click to expand...

This makes a lot of sense. But then I wonder why marquises are so expensive as well - are they also just wasteful? Because they are not really a very popular cut, are they? Great spread though - probably the spreadiest of the lot.

ItsMainelyYou said:
It's said that it is entirely dependent on make. Waste ratios. Rounds waste the most material and so on.
Though, I actually do think there's a small bit of fluctuation based upon what shape is currently popular as well added on the back end for retailers selling the finished products. It would make sense.
Click to expand...

It would make sense for it to be based on waste ratios. But I agree with you, there likely is some markup of both the most popular and the least popular shapes to both extract the most possible profit or compensate for longer lead time.
 
On second thought, sometimes 2 rounds from one octahedron result in little wasted rough.

4587.png
 
Popularity of the RB combined with reasonable yield from common rough shapes means more competition for the rough and higher prices.
Some of the precision cut high LP fancies trade off of round rap with the higher prices.
The other rough trades for less so the resulting stones can sell for less.
 
Karl_K said:
Popularity of the RB combined with reasonable yield from common rough shapes means more competition for the rough and higher prices.
Some of the precision cut high LP fancies trade off of round rap with the higher prices.
The other rough trades for less so the resulting stones can sell for less.
Click to expand...
Karl_K said:
Marq has so little sales volume that wierd pricing is not unusual.
Click to expand...

Thank you Karl! I never thought about it as a function of price for the rough, because I never thought it would fluctuate based on what could be cut from that piece. But now that you mention it it makes sense.

What is the full form of high LP fancies, by the way?
 
AllAboardTheBlingTrain said:
Thank you Karl! I never thought about it as a function of price for the rough, because I never thought it would fluctuate based on what could be cut from that piece. But now that you mention it it makes sense.
Click to expand...
Rough in general has almost always been sold based on what the expected polished is from the rough.
 
And this is why the fact that I want a bigger marquise is so difficult price wise!
 
Popularity. The less it’s wanted the less you pay .
 
I am reminded of the summer I took my then "going to be a senior in high school" daughter to Antwerp to see what her father did when he went there. We met one of my favorite vendors at his Friday night dinner with Family and arranged to meet with him Monday morning at his factory for a tour prior to going up to his office Tuesday morning for buying diamonds.

When we were on the tour, we saw an odd shaped diamond crystal having a window polished on one side, so they could look into the diamond to see clarity, etc once the skin of the crystal was clear.

The next morning, when we arrived at the office, they had that exact diamond on the desk and were discussing it. They played a little game with us. One of them greeted us in French, so I replied, then another in Spanish so Cissy replied, another in Japanese and I replied and the last said he knew neither of this would be able to reply and greeted us in Hebrew, he was correct. While all of these men were fluent in many languages, they did not know I had used most of my Japanese in my reply.

They then asked me if they could ask Cissy some questions, and I thanked them and and said to ask away.

They asked Cissy to help them settle the solution to what should be done with the crystal we had seen being windowed.

"We can cut a round of just over a carat from this crystal and a marquise of about 1.25 to 1.30 carats. What should we do?"

Cissy replied, "What is the value of the two diamonds?"

"We can sell the marquise for $100 more than the round?"

"How quickly can each diamond be sold?" Cissy asked.

"We can sell the round within the week after it is finished. The marquise could sell within the week, or it could take a year."

"Well then," said Cissy, "The answer is easy, Sell the round and reinvest and sell it again and again rather than take a chance for such a small extra profit on the marquise."

The men smiled at her and one of them turned to me, "That is exactly what we just decided. Wink, you should learn. to ask questions as well as your daughter!"
 
kenny said:
On second thought, sometimes 2 rounds from one octahedron result in little wasted rough.

4587.png
Click to expand...

True, if you think about waste by volume. If you think of it in terms of value, a piece of rough that you could cut a single large stone from would yield more value.

Therefore, the octahedron, yielding one medium and one small diamond is more costly. But demand for the rounds is strong enough for manufacturers to be able to get those compensating higher prices.
 
Two other factors come to mind. Diamond pricing in the trade is to a significant extent based upon Rap, which publishes two lists, one for rounds and one for pears. The pear list is used more broadly to price most fancy shapes. The differential between the two lists is significant with prices for rounds generally much higher.

Also, cutting compromises are taken much more liberally with fancy shapes to maximize yield, since GIA does not issue overall cut grades on any shape except round. This has the effect of making the per carat price for fancies generally lower still. There is much more variability in prices within each fancy shape for this reason as well.

Since GIA began issuing cut grades on rounds, cutting has improved considerably with the Triple Ex becoming a common standard for a well made round. So, with rounds today generally well cut and fancies generally less well cut, the disparity in pricing is greater than it probably should be.

Finding a well made fancy with a price competitive with the average for that shape, can represent a very good value!
 
A very interesting intellectual experiment!
But.....it points out how statistics ( comparing prices) can be so misleading.

Do a search on the major sites for any specific article. How much difference, percentage wise, between the cheapest and most expensive?
I just checked 1-1.05 G/VS2 and the range was from $4100-$6200+-
This makes it very difficult to plot prices reliably- not that Rap and others don't try to.....

Of course, there are a lot of variances that make sense... ie..a VS2 with a black carbon spot dead center, vs one with a harmless feather on the side.
But there are a lot of cases where there seems to be no rhyme or reason.
I've had countless discussions with cutters/dealers about price.
From my perspective- the value of the stone is determined by the market that day.
When I point out that a stone being offered is above market, and the seller says " But I paid $xxxx for it!"
I remind them that when the market is higher than what they paid, they're pretty quick to adjust upwards. When the market goes down, they seem to forget the times they've raised it.
Some people in the business are flexible and others are quite rigid.

All this goes into these statistics.
 
Texas Leaguer said:
True, if you think about waste by volume. If you think of it in terms of value, a piece of rough that you could cut a single large stone from would yield more value.

Therefore, the octahedron, yielding one medium and one small diamond is more costly. But demand for the rounds is strong enough for manufacturers to be able to get those compensating higher prices.
Click to expand...

Could you clarify a bit please, @Texas Leaguer? Because my understanding from what you said earlier was that the rough that can yield a single large stone is more valuable than one that yields a small and a medium. So does that mean that the rough yielding a medium and a small is less costly or more?
 
Rockdiamond said:
A very interesting intellectual experiment!
But.....it points out how statistics ( comparing prices) can be so misleading.

Do a search on the major sites for any specific article. How much difference, percentage wise, between the cheapest and most expensive?
I just checked 1-1.05 G/VS2 and the range was from $4100-$6200+-
This makes it very difficult to plot prices reliably- not that Rap and others don't try to.....

Of course, there are a lot of variances that make sense... ie..a VS2 with a black carbon spot dead center, vs one with a harmless feather on the side.
But there are a lot of cases where there seems to be no rhyme or reason.
I've had countless discussions with cutters/dealers about price.
From my perspective- the value of the stone is determined by the market that day.
When I point out that a stone being offered is above market, and the seller says " But I paid $xxxx for it!"
I remind them that when the market is higher than what they paid, they're pretty quick to adjust upwards. When the market goes down, they seem to forget the times they've raised it.
Some people in the business are flexible and others are quite rigid.

All this goes into these statistics.
Click to expand...

Still, I checked the PS search for prices of rounds (1-1.05 G VS2 Triple Ex None F) and the range was around 6k to 8.3k, and then then I checked cushions (1-1.05 G VS2 Ex Ex None F) and the range was around 2.8-5.9k… the most expensive cushion is still cheaper than the cheapest round. So clearly the averages are revealing.
 
AllAboardTheBlingTrain said:
Still, I checked the PS search for prices of rounds (1-1.05 G VS2 Triple Ex None F) and the range was around 6k to 8.3k, and then then I checked cushions (1-1.05 G VS2 Ex Ex None F) and the range was around 2.8-5.9k… the most expensive cushion is still cheaper than the cheapest round. So clearly the averages are revealing.
Click to expand...

Sorry @Rockdiamond i read my message over and it sounds a bit ruder than I intended. No offence meant :)
 
AllAboardTheBlingTrain said:
So clearly the averages are revealing.
Click to expand...

I didn't feel it was rude at all!!!
And- point taken. In spite of the wide variations within each shape, we can glean some info by comparing shapes.
I think yield makes a difference to a limited degree. The market really has more effect. Of course, this is based on my ( limited) perspective. I have always bought and shopped for polished diamonds.
There's no speculation when a specific stone is on the table.
 
I tried to double check these values but I think I messed up something in the search (I think I looked only for those stones that were HCA Ex). To eliminate that additional search criteria I looked up BN's inventory instead. Since they didnt have a field for GIA cut grade excellent, I picked only those stones that met their top 2 applicable cut category. I also wrote down how many pieces there were available for every shape:
  • round: $6770-11146 (62pcs)
  • Cushion: $3175-5135 (6pcs)
  • Emerald: $3825-6466 (15pcs)
  • Oval: $5736-$6592 (4pcs)
  • Princess: $4277-4569 (3pcs)
  • Pear: NA. (not a single one available. Had to go to VG-VG to find a single one, and it was about $7406).
  • Radiant: $4630-$5304 (2pcs)
  • Marquise: NA (not a single one available. Had to go to "Good" symmetry to find a single one, and it was about $7181).
  • Asscher: $4313 (1pc)
  • Heart: NA. (not a single one available. Had to go to VG symmetry to find 2, they were $4903 and $5304 respectively).
I'm not sure what this proves, other than rounds are clearly the most plentiful out there!
 
I don't know the exact numbers...but it always seemed to me that colorless, or near colorless rounds are at least 90% of the entire market...
 
AllAboardTheBlingTrain said:
I tried to double check these values but I think I messed up something in the search (I think I looked only for those stones that were HCA Ex). To eliminate that additional search criteria I looked up BN's inventory instead. Since they didnt have a field for GIA cut grade excellent, I picked only those stones that met their top 2 applicable cut category. I also wrote down how many pieces there were available for every shape:
  • round: $6770-11146 (62pcs)
  • Cushion: $3175-5135 (6pcs)
  • Emerald: $3825-6466 (15pcs)
  • Oval: $5736-$6592 (4pcs)
  • Princess: $4277-4569 (3pcs)
  • Pear: NA. (not a single one available. Had to go to VG-VG to find a single one, and it was about $7406).
  • Radiant: $4630-$5304 (2pcs)
  • Marquise: NA (not a single one available. Had to go to "Good" symmetry to find a single one, and it was about $7181).
  • Asscher: $4313 (1pc)
  • Heart: NA. (not a single one available. Had to go to VG symmetry to find 2, they were $4903 and $5304 respectively).
I'm not sure what this proves, other than rounds are clearly the most plentiful out there!
Click to expand...
I just want to point out that these numbers don't include specialty cushions such as Brian Gavin's Hearts and Arrows and Distinctive Gems AVC's. I think if you included those, you would have higher prices on the cushions.

My opinion -- there are a lot of really poorly cut cushions out there and the prices reflect that.
 
fel said:
I just want to point out that these numbers don't include specialty cushions such as Brian Gavin's Hearts and Arrows and Distinctive Gems AVC's. I think if you included those, you would have higher prices on the cushions.

My opinion -- there are a lot of really poorly cut cushions out there and the prices reflect that.
Click to expand...

I tried to stay away from super ideal prices by excluding also the speciality round and princess vendors, along with the cushions. My thought was the vast majority of the non-PS jewelry buying crowd - which is the vast majority of the jewelry buying crowd - will be purchasing GIA, and the most amount of diligence they will do is ensuring it’s Triple Ex (or Ex-Ex for fancies). So it’s a larger pool of knowledge to make the comparison from.

But you triggered my curiosity so I went to check Brian Gavin’s website. I had a bit of trouble finding a colour and clarity that had at least one stone available in both the H&A cushion and H&A round categories, but I finally found I VS1.

1-1.05, I VS1 BG cushion was for $6320 and round (there were 2) were for $8354-8382. The difference is not as stark, but there is still a 33% increase from cushion to round!

Also, WOW the prices for these cushions is so much higher than expected. The 3k-ish mark that stonealgo returned was for G VS2. It costs double that for an I VS1 from BG.

For fun, here is the average price for 1ct I VS1 round and cushion from stonealgo:

Round: $5269
Cushion: $2716
 
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AllAboardTheBlingTrain said:
For fun, here is the average price for 1ct I VS1 round and cushion from stonealgo:
Click to expand...

So the question you need to research and study for yourself, is why are these diamonds discounted so much from a super ideal vendor's prices. There is a reason if you can find it...
 
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