Emerald L/W ratio affecting flash and brilliance?

[mike734]

Hello all,


I was at a jeweler yesterday looking at a number of emerald cuts and the last stone he showed me had significantly more flash and brilliance than all the others. Then jeweler told me this is because it was a less rectangular stone (l/w: 1.19) This stone also had a 79% table and smaller corners than the other stones. It looked almost clearer and had that darker silverish essence you see in a round brilliant. There was another stone that had a 1.25 l/w and it also looked very nice compared to the others that were more 1.3-1.45.

Is there any truth to this idea that a less rectangular emerald will shine more? What factors could make an emerald have more flash and brilliance?

I'm looking at a stone online that has a great size for its weight but has a low crown height (9.9%) and crown angle of 38.9 deg. depth:63% table:66% L/W:1.4 Does this sound like it will make for a dull stone?

Thank you very much. I want to get a nice big stone for my girlfriend but I don't want it to be glassy and dull.

Any advice or tips for shopping for an emerald are greatly appreciated.

-Mike

 

[diamondseeker2006]

I recently bought an asscher (square emerald) from Good Old Gold. They did an ASET image to show light performance and also a video comparing 4 stones. There is no possible way to buy any fancy shape diamond blind. You need more than the grading report and a picture. I am not sure you can generalize about the performance based on the length/width ratio, but hopefully an expert will chime in on that aspect. I think there is more to the overall cut. A 79% table sounds absolutely huge...like the stone has a very large, flat top. It doesn't sound desirable to me. But if I were shopping for an emerald cut, I would use Good Old Gold because I can be certain I am getting an excellent cut stone.

Here is my asscher video for you to see performance of some very good to excellent step cuts:

http://www.youtube.com/watch?v=u7SBfNGxTFE&list=UUEV7slr-i-VduBBnfv9MxhA&index=2

 

[lambskin]

When looking for emerald cuts for possible ER I was shown a 3.5 ct E-F vv1 stone at a reputable place in the jewelers building in Chicago 25 years ago. Boy did this stone look big! Under the showroom lights it was pretty but under flourescent and day lights the stone looked like a giant ice cube. Cut makes all the difference!

 

[mike734]

Great, I appreciate the advice. If a stone falls within the criteria for a 1B Premium Cut according to AGA David Atlas grading, can it be assumed that this stone will have brilliance and look great. What factors are most critical in this grading system for an emerald, table, depth, crown height, sym. pol? All its parameters are close to ideal but the crown height is 9.9%. Does this typically make a stone lose some brilliance?

Thank you,
Mike

 

[diamondseeker2006]

You really need an ASET image to really know anything about the stones performance even when the numbers are good. Do you have pictures you can post?

 

[mike734]

I'll see if the vendor has an ASET machine. This is the one photo I have thus far, more should be coming.

 

[JulieN]

Impossible for us to tell from that kind of picture. Though I am confused about why the girdle is not resting flat on the black surface, or just an illusion from the shadows?