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I Wanna Know--What would a Concave Cut do for a Diamond's Light Performance?

voce

Ideal_Rock
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May 13, 2018
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3,726
I love concave cuts! Concave cuts seem like more work for the cutter, so I doubt I will see it on a diamond anytime soon, but I can't help but wonder!

Would a concave cut improve or worsen light return compared to MRB cuts, and why? :think::think:
 

Karl_K

Ideal_Rock
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Aug 4, 2008
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9,993
Not needed with the high RI of diamond.
 

diagem

Ideal_Rock
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Oct 21, 2004
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4,960
Also extremely difficult if not impossible to get a high polish on a groove.
Diamond hardness vairies by crystal orientation. Even if you could polish one side of a groove really well - the other side I imagine would be a nightmare.
@diagem ?
You have some polishing wheels that can do the trick (hence invisible setting grooves or heart shape clefts..., the only problem is, they might be polished but still look like an inclusion depending the position.
 

voce

Ideal_Rock
Joined
May 13, 2018
Messages
3,726
Not needed with the high RI of diamond.
I love the fireworks look of those thin long facets/grooves though!

I still didn't get an answer to the question I was asking.

@Garry H (Cut Nut) @diagem how important is the polish to the light return performance?
 

Wink

Ideal_Rock
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May 3, 2001
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7,484
If you are looking for the broader concave faceting that artists like Richard Homer do in colored gems, it is extremely difficult.

It may work for some of the facets, but when you cross a cleavage plane, there is a high danger that parts of the diamond will cleave rather than allow a curved facet.

I think you will find that it is not a practical way to facet a diamond.

Wink
 

Garry H (Cut Nut)

Super_Ideal_Rock
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Aug 15, 2000
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15,406
I love the fireworks look of those thin long facets/grooves though!

I still didn't get an answer to the question I was asking.

@Garry H (Cut Nut) @diagem how important is the polish to the light return performance?
Polish is very important for fire especially from all that I know.
But not the way that GIA measure it.
It is commonly thought and the message told on this forum that HPD and WF super dooper symmetry is why those diamonds have more fire.
I would argue that the fact that they are produced with state of the art equipment and TLC - the overall better polish is off the scale that GIA (and even AGS) grade.
e.g. GIA will ding a diamond where one facet has polish lines - but the overall polish - if it were measured on 0-100 scale - maybe the best of the best is an average of 97 and an average GIA X polish must be better than 85.
rambling - but I hope you get the message
 
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