Do pears face up smaller?

[Wyntery]

I've been looking for what feels like forever for a pear cut tanzanite to use in a pendant. I finally bought one which was 2.6ct, 10.34 x 7.75 x 5.35. My e-ring stone is a 2.5ct 10 x 8 oval tanzanite. For some reason my e-ring stone seems much bigger. Is it common for a pear of the same weight to 'look' smaller?

 

[the_mother_thing]

Different specific gravity properties will cause two different stones of the same carat weight to measure differently in size/mm.

 

[Wyntery]

Thanks JoCoCenn, both stones are tanzanite, that's why I was surprised by how small the pear looked.

 

[the_mother_thing]

Ahh, I missed that. My guess then is the pear appears smaller because of the "vacant" area at the pointy end vs the double rounded look of your oval, if that makes sense.

 

[LD]

If a stone is a deep one, it loses size face on compared to one that is shallow or average cut. Pears can differ wildly in appearance in the same carat weight. For example a long thin pointy pear will look like a polar opposite to a squat fat chunky pear! Both may weigh the same but look incredibly different.

 

[endless_summer]

My general impression is that pears face up quite large as compared to other cuts for the same weight. I second LD's comment - very true. One stone could be carrying more weight in it's belly for lack of better words. If you are concerned, you could consider having the pear weighed at a jewelers (assuming it's unset) - not sure where you purchased it, but I've had a stone that was supposed to be X weight, when really it was more than a half-carat less.

 

[T L]

Yes, I also agree with LD. I've seen some pears that face up rather well, and some fat and deep cut pears that face up small. The same goes for marquise shapes.

 

[Wyntery]

I think maybe JoCoJenn is right that what I'm seeing is the 'vacant' space at the tip.
I'm not going to bother sending it for tests/measure. It wasn't expensive and it's too light/violet for the project I had planned anyway, so I'm still looking...which I feel like I've been doing for over a year!

 

[the_mother_thing]

FWIW, LD is right also about the weight distribution being different for pears depending on how they are cut. I had a little "carat shock" when I received my Alex pear, thinking that for 2 ct, it would have been bigger. But it's a bit deep-cut, and the specgrav difference to what I was associating for a like sized diamond explained that.

Best wishes on finding the right stone for your project!

 

[chrono]

You have 2 things at play which explains why your pear faces up smaller than your oval and it isn't because a pear shape faces up smaller than an oval of the same carat weight.

2.6 ct pear = 10.34 x 7.75 x 5.35 mm
2.5 ct oval = 10 x 8 x 4.7 mm

1. Comparing the 2 measurements, it is clear that you will see the difference in size because the end of the pear comes to a tip, rather than being a rounded fat semi-circle of sorts even though both stones are approximately 10 x 8 mm.

2. So why such a big difference in surface area for 2 stones of approximately the same carat weight? Because they have different depth percentages. Even though you did not provide the depth in mm for the oval, by my estimate for your 2.5 carat oval tanzanite with a 10 x 8 mm measurement worked out to have a depth of 4.7 mm thereabouts. So, you'll see that the oval is much shallower than the pear. So which stone is deep and which one is shallow? I continued my calculations and found the pear to measure correctly whilst the oval is shallow, hence it faces up large for its carat weight.

Mystery solved.

 

[Wyntery]

Chrono, your expertise astounds me! Please tell me you do this for your day job, if not, your talents are wasted!

 

[chrono]

I'm not in the trade but I do mathematics related calculations at work.

 

[LoversKites]

Makes sense, thanks for explaining that.