Diamond weight question???

[AndyDiamond]

This may sound like a dumb question, but I am wondering if all diamonds weigh the same amount for the same area of volume? Or do different diamonds from different mines, or inclusions weight slightly different?

What got my attention was that I expect for the same carat weight if the spread is larger, the stone will be cut more shallow, but I noticed that is not always the case.

 

[rubybeth]

This may sound like a dumb question, but I am wondering if all diamonds weigh the same amount for the same area of volume? Or do different diamonds from different mines, or inclusions weight slightly different?

What got my attention was that I expect for the same carat weight if the spread is larger, the stone will be cut more shallow, but I noticed that is not always the case.

I'm not sure about all that area of volume stuff, or inclusions, but different shape cuts face up different sizes, because of their needed depth for that cut. For example, a 1 carat round should be about 6.5-6.7mm across the top, whereas a 1 carat square princess cut will be more like 5.5mm. That's a pretty significant difference. I think of it like a cone vs. a square pyramid. Pears and ovals are fairly shallow cuts, so a 1 carat pear will be more like 5.5x8mm.

 

[kenny]

"Area of volume"
I think you mean just, volume.

Area is a two dimensional thing.
Area has no mass, so gravity cannot act on it, so it cannot be weighed.

Volume is 3-dimensional thing.
It has mass so gravity affects it so it can be weighed.
(Even a piece of paper has a third dimension though tiny, its thickness.)

Diamond is one single material with one density, specific gravity, or weight for volume.

I guess in theory impurities, like boron for blues and nitrogen for yellow would result in a slightly different weight.
Certain inclusions, like garnets, may not be pure carbon, but I'd guess the difference would be almost not measurable and certainly NOT commercially significant.

 

[MissStepcut]

This may sound like a dumb question, but I am wondering if all diamonds weigh the same amount for the same area of volume? Or do different diamonds from different mines, or inclusions weight slightly different?

What got my attention was that I expect for the same carat weight if the spread is larger, the stone will be cut more shallow, but I noticed that is not always the case.

I think there are two possible places to look for the discrepancy: girdle (thicker girdles are "hiding" weight) and pavilion bulge.

 

[kenny]

I'm wondering if this question is related to face up size for a given weight.
Shallow shapes face up large while deep shapes face up small - unless you set them sideways.

Visualize an orange and a pickle of the same weight.
A pickle on its side has a large face up area for it's weight.
But it you turn it so you are looking at the end of the pickle it has very small face up size for its weight.

An orange has the same face up size regardless of how you turn it.

So shape and how you view that shape can have a great effect on the appearance of size for a given weight.

To put it another way, a one-carat diamond could be a three inch square if it was thin enough or it could appear as the diameter of a paper clip if it was long enough.

 

[MissStepcut]

He said he's looking at depth too, guys. I bet pavilion bulge is to blame here, if we're talking about FCDs.

 

[diamondseeker2006]

I think he is looking at rb's. Girdle can hide weight, too. (oops, I see that was already posted)

 

[AndyDiamond]

To clarify,

I am comparing only round brilliants, apples to apples comparison. Why would the pavillion budge be a factor only for fancy colored diamonds? I think the girdle thickness probably explains it.

 

[MissStepcut]

To clarify,

I am comparing only round brilliants, apples to apples comparison. Why would the pavillion budge be a factor only for fancy colored diamonds? I think the girdle thickness probably explains it.

It wouldn't only matter for colored diamonds (it would be something to consider for step-cut stones too) but since they're cut for color, the cutting patterns may include significant pavilion bulge. It also spares weight.